SAXIFRAGALES Dumortier Main Tree, Synapomorphies

Hamamelidanae Takht., Sist. Filog. Cvetk. Rast. [Syst. Phylog. Magnolioph.]: 113. 4 Feb 1967; Hamamelididae Takht., Sist. Filog. Cvetk. Rast. [Syst. Phylog. Magnolioph.]: 461. 4 Feb 1967, pro parte; Saxifraganae Reveal in Phytologia 76: 4. 2 Mai 1994

Fossils Archamamelis bivalvis is represented by fossil flowers from the Late Santonian to the Early Campanian of Sweden. The hexamerous or heptamerous flowers have a bicyclic perianth, one series of stamens, one whorl of staminodia, and a gynoecium of three connate carpels. Divisestylus from the Turonian of New Jersey comprises fossil pentamerous flowers with alternipetalous stamens containing striate pollen, an intrastaminal nectariferous disc and two carpels connate at stigmatic and ovary regions; the capsules were apically dehisced and the stomata anomocytic. The Coniacian Lindacarpa pubescens from eastern Siberia is a spherical female inflorescence, the flowers of which having connate sepals and a semi-inferior gynoecium of two connate carpels. Microaltingia apocarpela, from the Turonian of New Jersey, consists of stalked spherical female inflorescences with two basally connate semi-inferior ovaries per flower.

Habit Bisexual, monoecious, andromonoecious, polygamomonoecious, dioecious, androdioecious or polygamodioecious, evergreen or deciduous trees, shrubs or suffrutices (rarely lianas), perennial, biennial or annual herbs. Many representatives are succulent and/or xerophytic with CAM-physiology. Sometimes aquatic.

Vegetative anatomy Roots often diarch. Phellogen ab initio subepidermal, pericyclic or outer-cortical. Secondary lateral growth normal or absent. Tension wood sometimes present. Vessel elements usually with scalariform (sometimes simple, rarely reticulate) perforation plates; lateral pits scalariform, opposite or alternate (rarely reticulate), simple or bordered pits, non-septate. Vestured pits sometimes present. Imperforate tracheary elements fibre tracheids or libriform fibres (sometimes tracheids) with simple or bordered pits, usually non-septate, or absent (sometimes also vasicentric tracheids). Wood rays uniseriate or multiseriate, homocellular or heterocellular, or absent. Axial parenchyma apotracheal diffuse or diffuse-in-aggregates, or paratracheal scanty, vasicentric, unilateral or banded, or absent. Sieve tube plastids Ss or S₀ type. Nodes usually 3:3, trilacunar with three leaf traces (sometimes 1:1–3 or ≥5:≥5, unilacunar or multilacunar with one or several traces). Cystoliths sometimes numerous. Secretory cells sometimes with proanthocyanidins and/or ellagitannins. Idioblasts with cyanogenic compounds or druses unusual. Schizolysigenous resinous canals with balsam sometimes abundant. Tanniniferous cells sometimes frequent. Prismatic calciumoxalate crystals, druses or crystal sand often present (rarely elongate crystals or styloids).

Trichomes Hairs unicellular or multicellular, uniseriate or multiseriate, often branched (furcate, stellate, sometimes rarely arachnoid), stalked or unstalked, or absent (sometimes tufted, peltate, clavate or vesicular; often with multicellular apical gland); glandular hairs sometimes frequent, sometimes peltate or lepidote; prickles sometimes abundant on branch epidermis.

Leaves Usually alternate (spiral or distichous; sometimes opposite or verticillate), simple or pinnately or palmately compound, entire or lobed, with usually conduplicate or involute (sometimes flat or curved, rarely plicate, supervolute or convolute) ptyxis (leaves sometimes succulent). Stipules usually absent (sometimes intrapetiolar, rarely pairwise); leaf base usually absent (sometimes sheathing). Colleters sometimes present. Petiole vascular bundle transection arcuate or annular, sometimes with medullary or adaxial bundles. Venation pinnate or palmate, actinodromous, eucamptodromous, brochidodromous or craspedodromous; lateral veins often running out into (glandular) leaf teeth. Stomata usually anomocytic or paracytic (sometimes anisocytic or diacytic, rarely helicocytic), often only on adaxial side of lamina. Cuticular wax crystalloids usually as tubuli (often clustered tubuli [Berberis type, at least in some woody Saxifragales], sometimes as rodlets, threads or platelets), chemically often dominated by nonacosan-10-ol. Domatia as pockets or hair tufts, or absent. Mesophyll and petiolar cortex sometimes with calciumoxalate as druses or single prismatic crystals. Leaf margin usually serrate (sometimes entire, crenate or biserrate); leaf teeth usually rosoid, sometimes platanoid (glandular with cavity, lateral veins almost reaching teeth), fothergilloid (with transparent glandular apex, lateral veins almost reaching teeth) or chloranthoid (with persistent transparent swollen structure, into which high order lateral veins proceed).

Inflorescence Terminal or axillary, racemes, spikes or heads, or raceme-, spike- or head-like, pleio-, di- or monochasia, thyrsoids, fasciculate, panicles, corymbs, racemes or cincinnate (flowers rarely solitary). Floral prophylls (bracteoles) sometimes absent.

Flowers Usually actinomorphic (rarely zygomorphic). Hypanthium sometimes present. Epigyny or half epigyny (sometimes hypogyny). Sepals (two to) four or five (sometimes eight or ten), with imbricate or valvate aestivation, free (sometimes connate at base; sometimes spiral or absent). Petals (two to) four or five (to 13), with imbricate or valvate aestivation, free (sometimes spiral or absent). Nectary and disc absent, or nectariferous disc intrastaminal.

Androecium Stamens (one to) four or five (to more than 100), usually whorled, alternisepalous, or (4–)5+(4–)5, diplostemonous or obdiplostemonous (sometimes spiral). Filaments usually free (rarely connate at base, usually free from tepals (rarely epipetalous). Anthers usually basifixed (usually with filament attached at basal pit; rarely dorsifixed), usually non-versatile, usually tetrasporangiate (rarely disporangiate), usually latrorse (sometimes introrse or extrorse), usually longicidal (dehiscing by longitudinal slits; rarely valvate or with a basal pore or short apical slits). Tapetum secretory. Staminodia usually absent (sometimes antepetalous; female flowers sometimes with staminodia).

Pollen grains Microsporogenesis simultaneous. Pollen grains 2–3-colpate, 2–3-colpor(oid)ate or polypantoporate (sometimes diporate, rately triporate), shed as monads, bicellular at dispersal. Exine tectate or semitectate, with usually columellate (rarely granular) infratectum, perforate, reticulate, rugulate or striate, verrucate, echinulate, spinulate, scabrate or psilate.

Gynoecium Pistil composed of one to 32, usually connate (sometimes free, at least in distal part) carpels, sometimes unsealed distally-ventrally (sometimes spiral); carpel plicate. Ovary inferior or semi-inferior (sometimes superior), unilocular (apocarpy) to quadrilocular. Stylodia two to numerous, free, or absent. Stigmas usually capitate (sometimes decurrent), papillate, Dry or Wet type. Pistillodium usually absent (male flowers sometimes with pistillodium/pistillodia).

Ovules Placentation axile or parietal (sometimes apical or marginal to laminar). Ovules one to more than 100 per carpel, anatropous (sometimes hemianatropous), pendulous, horizontal or ascending, apotropous or epitropous, usually bitegmic (rarely unitegmic), usually crassinucellar (sometimes tenuinucellar). Micropyle usually bistomal, often Z-shaped (zig-zag; rarely exostomal). Nucellar cap sometimes present. Megagametophyte usually monosporous, Polygonum type (rarely disporous, Allium type). Synergids often with a filiform apparatus, rarely haustorial. Endosperm development usually cellular (rarely helobial or nuclear). Endosperm haustorium chalazal or absent. Embryogenesis solanad, caryophyllad or chenopodiad.

Fruit Usually a follicle, a septicidal and/or loculicidal capsule or a nut (sometimes a drupe, a berry, or an assemblage of follicles or nutlets, or a syncarp consisting of follicles or septicidal capsules, rarely a schizocarp with nut-like mericarps).

Seeds Aril usually absent (sometimes funicular aril enclosing seed entirely or partially). Seed coat testal or exotestal (sometimes mesotestal or endotegmic). Exotestal cells often with outer wall (sometimes radial walls) thickened (sometimes partially crushed). Inner pigmented layer often present. Tegmen usually crushed (inner exotegmic layer sometimes pigmented). Endotegmen sometimes with thick sclerotic, cutinized, tanniniferous and/or crystalliferous cell walls. Perisperm usually not developed (sometimes more or less developed). Endosperm copious or sparse, oily, proteinaceous (rarely starchy). Embryo large or small, straight or curved, without chlorophyll. Cotyledons two. Germination phanerocotylar.

DNA Insertion present in 18S rDNA. I copy of nuclear gene RPB2 lost. Mitochondrial intron coxII.i3 sometimes lost.

Phytochemistry Flavonols (kaempferol, quercetin, myricetin, apigenin, luteolin, etc.), afzelechin (a flavan-3-ol), methylated and non-methylated flavones, acylated flavonol glycosides, pelargonidin, chalcones, dihydrochalcones, cyanidin, delphinidin, mono- and sesquiterpenes, oleanolic acid derivatives, toxic bufadienolides, Group I carbocyclic iridoids (e.g. daphylloside, monotropein, asperuloside, daphniphylloside), ellagic and gallic acids, bergeniin (C-glycoside of gallic acid), ellagic or gallic acid based hydrolyzable tannins (tellimagrandin I and II etc.), condensed tannins (from procyanidin or prodelphinidin), proanthocyanidins (prodelphinidins), myriophyllin, pyridine alkaloids, glycosides (e.g. paeonol, paeonolide, paeonoside, paeoniflorin, oxypaeoniflorin, benzoylpaeoniflorin and alliflorin), isoleucine-, tyrosine- or valine-derived cyanogenic compounds, coumaric acid, arbutin, acetophenones, galloylic esters, and germacrane-like compounds present. Squalene alkaloids of the daphniphyllin group rare. Saponins not found.

The first main clade, with the topology [Paeoniaceae+[Altingiaceae+[Hamamelidaceae+ [Cercidiphyllaceae+Daphniphyllaceae]]]], has the synapomorphies leaves with basically palmate venation; and absence of mitochondral intron coxII.i3. The clade [Altingiaceae+ [Hamamelidaceae+[Cercidiphyllaceae+Daphniphyllaceae]]] is characterized by cuticular wax crystalloids as tubuli, dominated by nonacosan-10-ol; usually racemose inflorescence; absence of pedicel; valvicidal anther with apically protruding connective; and an elongate embryo. Cercidiphyllaceae and Daphniphyllaceae share the potential synapomorphies dioecy; small flowers; absence of petals; and hypogyny.

The second main clade [[Crassulaceae+[Aphanopetalaceae+[Tetracarpaeaceae+[Haloragaceae+Penthoraceae]]]]+[[Iteaceae+Pterostemonaceae]+[Grossulariaceae+Saxifragaceae]]] has the following potential synapomorphies, according to Stevens (2001 onwards): superficial phellogen; vessel elements with simple perforation plates; petiole bundle transection arcuate; cuticular wax crystalloids not as tubuli; ovules apotropous; and calyx persisting as withered. The clade [Crassulaceae+[Aphanopetalaceae+[Tetracarpaeaceae+[Haloragaceae+Penthoraceae]]]] has the synapomorphies: endodermis usually present in stem; nodes 1:1; absence of stipules; and tricolporate pollen grains. The [[Iteaceae+Pterostemonaceae]+[Grossulariaceae+Saxifragaceae]] clade has spiral leaves; presence of hypanthium; antesepalous stamens as many as sepals; ovules numerous per carpel; and a septicidal capsule. Iteaceae and Pterostemonaceae share the features: presence of stipules; one style; axile placentation; sparse endosperm; and presence of flavone-C-glycosides. Likewise, Grossulariaceae and Saxifragaceae share the characters two or three connate carpels; and sometimes helobial endosperm development.

Distribution Eastern Mediterranean to eastern Himalayas, India, China, Taiwan, Indochina, West Malesia, eastern and northeastern North America, Mexico, Central America.

Fossils Altingiaceae are richly represented by Cenozoic fossils, particularly from the Miocene and the Pliocene. Infructescences of Steinhauera from Eocene layers in Europe resemble those in Liquidambar.

Vegetative anatomy Phellogen ab initio superficial. Vessel elements with scalariform perforation plates; lateral pits scalariform or opposite, simple pits. Imperforate tracheary xylem elements ? with bordered pits, non-septate. Wood rays uniseriate or multiseriate, homocellular. Axial parenchyma apotracheal diffuse, or paratracheal scanty, or absent. Sieve tube plastids Ss type. Nodes trilacunar? Schizolysigenous resinous canals with balsam abundant in most tissues. Calciumoxalate crystals?

Leaves Alternate (spiral), simple, usually palmately lobed (rarely entire), with flat-conduplicate ptyxis. Stipules (intra?)petiolar, small, usually caducous; leaf sheath absent. Petiole vascular bundle transection annular; petiole with medullary bundles. Venation palmate, usually actinodromous (sometimes camptodromous). Stomata paracytic. Cuticular wax crystalloids as tubuli? Domatia as pockets or hair tufts. Leaf margin usually serrate (rarely entire); leaf teeth platanoid (glandular with cavity).

Inflorescence Terminal, cymose (condensed panicles); male inflorescences capitula in spike- or raceme-like partial inflorescences; female inflorescences globular, with intercarpellary outgrowths corresponding to sterile flowers.

Flowers Actinomorphic, small. Epigyny? Tepals absent (or as tiny rudimentary scales?). Nectary absent. Disc absent.

Androecium Stamens four to ten. Filaments free. Anthers basifixed, non-versatile, tetrasporangiate, latrorse, longicidal (dehiscing by longitudinal valves or slits). Tapetum secretory. Staminodia absent.

Pollen grains Microsporogenesis simultaneous. Pollen grains triporate to polypantoporate, shed as monads, bicellular at dispersal. Exine semitectate, with columellate infratectum, finely reticulate.

Gynoecium Pistil composed of two connate carpels; carpels with various orientation (sometimes transversely orientated), unsealed, only lower carpels fertile. Ovary inferior?, bilocular. Style absent. Stigmas much decurrent, with multicellular appendages (sometimes unicellular papillae?), Dry type. Pistillodium absent.

Ovules Placentation axile. Ovules c. 20 to 47 (only lower ovules fertile) per carpel, anatropous?, horizontal, apotropous, bitegmic, crassinucellar. Micropyle usually bistomal? (sometimes endostomal). Outer integument approx. two cell layers thick. Inner integument approx. five cell layers thick. Megagametophyte monosporous, Polygonum type. Endosperm development ab initio nuclear. Endosperm haustoria? Embryogenesis?

Fruit Septicidal (and occasionally loculicidal) lignified capsules (sometimes more or less connate). Endocarp cells thickened, transversely elongate relative to longitudinal axis of fruit.

Seeds Aril absent. Seed winged (wings developed from elongation of integuments surrounding micropyle). Seed coat testal (or exotegmic?). Exotestal cell walls often lignified. Mesotestal cells more or less sclerotized. Endotestal cells oblong, with lignified walls. Exotegmen well developed? Endotegmen? Perisperm not developed. Endosperm poorly developed. Embryo long, straight, chlorophyll? Cotyledons two, flattened. Germination phanerocotylar.

Phytochemistry Flavonols (quercetin, myricetin), cyanidin, Group I carbocyclic iridoids (daphylloside, monotropein), ellagic acid, tannins, and proanthocyanidins (prodelphinidins) present. Cyanogenic compounds not found.

Use Ornamental plants, timber, carpentry, medicinal plants (gum from Liquidambar orientalis).

Habit Bisexual, evergreen climbing shrub or liana. Lenticels elevated and prominent.

Vegetative anatomy Phellogen ab initio superficial. Endodermis distinctly delimited, as innermost cortical layer. Pericyclic fibres absent. Vessel elements with scalariform perforation plates; lateral pits?, bordered pits. Imperforate tracheary xylem elements fibre tracheids with bordered pits?, non-septate. Wood rays uniseriate homocellular or multiseriate heterocellular. Axial parenchyma apotracheal diffuse, or paratracheal scanty. Ray parenchyma cells starchy. Sieve tube plastids Ss type? Nodes 1:1(–2), unilacunar with one bifid leaf trace. Crystals?

Leaves Usually opposite (rarely verticillate), simple, entire, with ? ptyxis. Stipules? present on both sides of nodes, modified into tooth-like colleters; leaf sheath absent. Petiole bundle transection arcuate?; petiole with usually three (rarely one) vascular bundles. Venation pinnate. Stomata anomocytic. Cuticular waxes? Leaf margin entire or serrate; leaf teeth one-veined, salicoid, without glands.

Flowers Actinomorphic. Hypanthium present, short. Half epigyny. Sepals four (or five), with imbricate aestivation, persistent, largely free. Petals four (or five), rudimentary and visible only as young, free, or absent. Tepals connate at base into tube. Nectary? Disc absent.

Androecium Stamens usually eight (sometimes ten). Filaments connate at base into a tube, adnate to tetals (epitepalous). Anthers elongate, almost basifixed, non-versatile, tetrasporangiate, latrorse-introrse, longicidal (dehiscing by longitudinal slits); connective prolonged. Tapetum secretory? Staminodia absent.

Pollen grains Microsporogenesis simultaneous? Pollen grains tricolporate, shed as monads, bicellular at dispersal. Exine tectate, with columellate? infratectum, rugulate-stellate.

Gynoecium Pistil composed of four connate antepetalous carpels. Ovary semi-inferior, quadrilocular. Style single, quadrilobate, with four stylar canals. Stigma papillate, type? Pistillodium?

Ovules Placentation apical-axile. Ovule usually one (rarely two) per carpel, anatropous, pendulous, epitropous, bitegmic, crassinucellar. Funicle long, thick. Micropyle bistomal. Outer integument ? cell layers thick. Inner integument ? cell layers thick. Parietal tissue? Megagametophyte monosporous, Polygonum type. Endosperm development? Endosperm haustoria? Embryogenesis?

Seeds Aril absent. Seed reniform or hippocrepomorphic, often winged or with long hairs. Testa? Tegmen? Perisperm not developed. Endosperm copious?, fleshy. Embryo curved, chlorophyll? Cotyledons two. Germination?

Fossils Reports of Cercidiphyllaceae from the Cretaceous, based on leaves and fruits, are ambiguous. On the other hand, the Paleocene Joffrea speirsiae from Alberta (Canada) has an elongated receptacle and a bicarpellate pistil with the adaxial sutures directed against one another, resembling extant Cercidiphyllaceae. Similar fossils are known from the Maastrichtian of western North America. Fossilized leaves and inflorescences (with flowers possessing sometimes pentamerous perianth) indicate that Cercidiphyllum was widely distributed in the Northern Hemisphere during the Cenozoic.

Habit Usually dioecious (rarely monoecious), deciduous trees with very distinct difference between long and short shoots.

Vegetative anatomy Phellogen ab initio outer-cortical. Primary medullary rays narrow. Primary stem with continuous vascular cylinder. Vessel elements with scalariform perforation plates; lateral pits opposite to scalariform, simple and/or bordered pits. Imperforate tracheary xylem elements fibre tracheids with bordered pits, non-septate. Wood rays biseriate with uniseriate ends, heterocellular. Axial parenchyma apotracheal diffuse?, or paratracheal scanty or banded, or absent. Tyloses abundant. Sieve tube plastids Ss type. Nodes on short shoots unilacunar (with one leaf trace?), on long shoots trilacunar (with three traces?). Parenchyma with prismatic calciumoxalate crystals.

Leaves Usually opposite (rarely verticillate) on long shoots, a few alternate on short shoots, simple, entire, with involute ptyxis. Stipules adaxial-petiolar (intrapetiolar), small, caducous; leaf sheath absent. Petiole vascular bundles? Leaf bases on long shoots cuneate, on short shoots cordate. Venation palmate brochidodromous. Stomata anomocytic. Cuticular wax crystalloids as clustered tubuli (Berberis type), chemically dominated by nonacosan-10-ol. Mesophyll and petiolar cortex with calciumoxalate as druses or single prismatic crystals. Leaf margin on long shoots entire to finely serrate, on short shoots crenate; leaf teeth chloranthoid (with persistent transparent swollen structure, into which higher order lateral veins proceed).

Inflorescence Terminal, dense, few-flowered on sympodial short shoots; female inflorescences capitate pseudanthia, with two to eight flowers, often surrounded by involucre of sepaloid bracts; male inflorescences raceme-like, short, with (lower flowers) or without (upper flowers) bracts. Prophyll adaxial.

Flowers At least male flowers zygomorphic (with stamens on abaxial side). Hypogyny? Tepals absent. Nectary absent. Disc absent.

Androecium Stamens 16–35, in fascicles (flowers?) each with one to 13 stamens. Each staminal fascicle (flower?) subtended by a single bract. Filaments long, thin, free. Anthers basifixed, non-versatile, tetrasporangiate, latrorse, longicidal (dehiscing by longitudinal slits); connective somewhat prolonged at apex. Tapetum secretory, with binucleate cells. Staminodia absent.

Pollen grains Microsporogenesis simultaneous. Pollen grains tricolpate, shed as monads, bicellular at dispersal. Exine tectate, with columellate infratectum, perforate or finely reticulate, beset with supratectal verrucae.

Gynoecium Pistil composed of one carpel (monocarpellate); carpel plicate, somewhat stipitate, with abaxial ventral suture. Ovary superior?, unilocular (apocarpy). Stylodium long. Stigma decurrent its entire length, papillate, Dry type. Pistillodium absent.

Ovules Placentation laminal-lateral (marginal). Ovules c. 15 to c. 30 per carpel, anatropous, pendulous, apotropous, bitegmic, crassinucellar. Micropyle bistomal. Outer integument four or five cell layers thick. Inner integument two or three cell layers thick. Chalazal end elongating into a wing-like structure during maturation. Megagametophyte monosporous, Polygonum type. Endosperm development ab initio cellular. Endosperm haustoria? Embryogenesis caryophyllad.

Fruit A follicle. Groups of adjacent follicles forming a syncarp (multifolliculus).

Seeds Aril absent. Seed small, with a chalazal wing-like appendage with hairpin-like vascular bundle. Seed coat testal. Testa indistinct. Exotestal cells enlarged, somewhat thickened. Tegmen tanniniferous, degenerating. Perisperm not developed. Endosperm poorly developed, oily, with one large suspensor cell. Embryo large, straight, well differentiated, without chlorophyll. Cotyledons two. Germination phanerocotylar.

Phytochemistry Flavonols (kaempferol, quercetin), cyanidin, chalcones, dihydrochalcones, ellagic acid, and tannins present. Cyanogenic compounds and saponins not found.

Saint-Hilaire, Expos. Fam. Nat. 2: 123. Feb-Apr 1805 [‘Crassuleae’], nom. cons.

Sempervivaceae Juss., Gen. Plant.: 207. 4 Aug 1789 [‘Sempervivae’]; Sedaceae Roussel, Fl. Calvados, ed. 2: 291. 1806 [’Sedoideae’]; Cotyledonaceae Martinov, Tekhno-Bot. Slovar: 168. 3 Aug 1820 [‘Cotyledones’]; Rhodiolaceae Martinov, Tekhno-Bot. Slovar: 546. 3 Aug 1820 [‘Rhodioleae’]; Sempervivales Juss. ex Bercht. et J. Presl, Přir. Rostlin: 238. Jan-Apr 1820 [‘Semperviveae’]; Tillaeaceae Martinov, Tekhno-Bot. Slovar: 635. 3 Aug 1820; Sedales Reichb., Bot. Damen: 462. 1828 [’Sediflorae’]; Crassulales Link, Handbuch 2: 18. 4-11 Jul 1829 [’Crassulaceae’]; Sedineae Rchb., Deutsch. Bot. Herb.-Buch: lxiii. Jul 1841 [‘Sediflorae’]; Crassulopsida Brongn., Enum. Plant. Mus. Paris: xxviii, 106. 12 Aug 1843 [’Crassulineae’]

Distribution Temperate, subtropical and alpine regions on both hemispheres, with their largest diversity in Mexico and southern Africa.

Habit Usually bisexual (rarely unisexual), usually perennial (rarely annual or biennial) herbs, suffrutices or evergreen shrubs (rarely trees or epiphytes). Leaf succulents. Usually xerophytes. Rarely aquatic (i.a. Crassula aquatica). Many species produce adventitious roots from broken leaves; some species form bulbils along leaf margins or in inflorescences.

Vegetative anatomy Mycorrhiza usually absent. Roots usually fibrous. CAM physiology frequently present; acid metabolism often Crassulaceae type (via isocitrate). Mycorrhiza absent. Phellogen ab initio usually subepidermal (sometimes cortical). Young stem with separate vascular bundles. Cortical and/or medullary vascular bundles present or absent. Endodermis present or absent. Secondary lateral growth usually normal (rarely anomalous). Vessel elements (usually short) usually with simple (in Sedum rarely reticulate) perforation plates; lateral pits scalariform(-reticulate) or alternate, simple pits? Imperforate tracheary xylem elements libriform fibres with simple pits, non-septate, or absent. Wood rays absent. Axial parenchyma usually paratracheal scanty vasicentric. Wood elements often storied. Phloem little developed. Sieve tube plastids S₀ type, without starch or protein inclusions. Nodes 1:1, 1:2, 1:3, unilacunar with one to three leaf traces, or ≥3:≥3, trilacunar to multilacunar with several traces. Cork tissue usually without resin. Prismatic crystals or crystal sand present or absent.

Trichomes Hairs unicellular or multicellular, usually uniseriate or biseriate (sometimes furcate, stellate, rarely arachnoid), vesicular hairs frequent; glandular hairs often frequent.

Leaves Usually alternate (spiral) or opposite (in some species of Sedum verticillate), usually simple (rarely pinnately or palmately compound), usually entire (rarely lobed), often round in cross-section, usually succulent, with curved to flat ptyxis. Stipules and leaf sheath absent. Petiole vascular bundle transection arcuate. Venation pinnate or palmate, camptodromous or reticulate. Stomata usually anisocytic (rarely helicocytic with second ring of subsidiary cells outside anisocytic cell configuration), often on both laminal surfaces (amphistomatic). Cuticular wax crystalloids as platelets, rodlets (sometimes as elongated rosettes, sometimes longitudinally furrowed), threads or lobate to smooth platelets, chemically characterized by high amounts of triterpenoids. Hydathodes abundant. Epidermis often with mucilage cells. Lamina usually without palisade tissue. Mesophyll in succulent leaves often with outer chlorenchyma grading into inner chlorophyll-poor water storage parenchyma. Tanniniferous cells abundant. Crystals and druses frequent (sometimes crystal sand). Leaf margin serrate, crenate or entire.

Inflorescence Usually terminal (rarely axillary), thyrsoid, pleio-, di- or monochasium (cincinnus or corymb; rarely panicle, raceme- or spike-like). Extrafloral nectaries rarely (Adromischus) present.

Flowers Usually actinomorphic (rarely zygomorphic). Hypanthium present. Hypogyny to half epigyny. Sepals (three to) five (to 32), with imbricate aestivation, free or connate at base. Petals (three to) five (to 32), with quincuncial, cochlear, contorted, imbricate or valvate aestivation, free or entirely or partially connate into a tube. Nectaries as abaxial usually scale-like or elongate (in ’Monanthes’ petaloid) outgrowths from carpel bases. Disc absent.

Androecium Stamens usually twice as many (sometimes as many) as petals, usually in two whorls, obdiplostemonous (sometimes a single whorl, antesepalous). Filaments usually free (sometimes connate at base), free from or (when sympetalous) adnate to corolla tube (antepetalous stamens inserted somewhat higher up than antesepalous stamens). Anthers basifixed, non-versatile, tetrasporangiate, usually latrorse (rarely somewhat introrse), longicidal (dehiscing by longitudinal slits). Tapetum secretory, with uninucleate cells. Staminodia usually absent (female flowers often with staminodia).

Pollen grains Microsporogenesis simultaneous. Pollen grains usually tricolporate, shed as monads, bicellular at dispersal. Exine tectate or semitectate, with columellate infratectum, reticulate or rugulate, usually with striae.

Gynoecium Carpels (three to) five to ten (to 32), as many as petals, antepetalous, usually free (sometimes connate at base; in Crassula pageae entirely connate), sometimes stipitate. Ovary superior to semi-inferior, unilocular (apocarpy). Stylodia usually short (style rarely single, branched), usually with abaxial nectariferous scale at base (secreting nectar through stomata). Stigmas small, usually apical, capitate to punctate, papillate, usually Dry (sometimes Wet) type. Pistillodia usually absent (male flowers often with pistillodia).

Ovules Placentation usually marginal to laminar (rarely parietal). Ovule one to usually numerous per carpel, anatropous, pendulous to horizontal, bitegmic, crassinucellar or (in Crassuloideae) tenuinucellar. Micropyle usually bistomal (sometimes exostomal or endostomal). Outer integument approx. two cell layers thick. Inner integument two or three cell layers thick. Nucellar cap approx. four cell layers thick. Hyponucellus (part of megasporangium present below developing megagametophyte) strongly enlarged during development (Sedum and Crassula types of megasporangium). Megasporangial apex sometimes extending beyond outer integument; apical cell seemingly subpalisade. Megasporocyte usually single (archespore sometimes multicellular). Megaspore haustoria present in some species. Megagametophyte usually monosporous, Polygonum type (in Hylotelephium disporous, Allium type). Synergids sometimes haustorial (synergidal haustoria present). Antipodal cells sometimes proliferating and haustorial. Micropylar suspensor haustorium often well developed. Endosperm development usually cellular (rarely helobial or nuclear; endosperm in e.g. Crassula aquatica reduced with chalazal chamber of bicellular stage not dividing but becoming haustorial). Endosperm haustorium chalazal. Embryogenesis caryophyllad.

Fruit Usually an assemblage of follicles (rarely nutlets or a capsule; in Diamorpha secondarily fused into a syncarp).

Seeds Aril absent. Testa usually with papillae or longitudinal ridges. Outer wall of exotestal cells thickened. Two layers crushed. Inner exotegmic layer pigmented. Perisperm not developed. Endosperm sparse (thin layer surrounding hypocotyl), oily, or absent. Suspensor uniseriate; basal suspensor cell with hypha-like haustorial branches. Embryo small, straight, elongate, without chlorophyll. Plumule absent. Cotyledons two, fleshy. Germination phanerocotylar.

Cytology n = 4-≥22 – Karyologically very variable; even the base number varying at least between x = 5 and x = 37 (especially in Sedum; S. suaveolens has the highest haploid chromosome number among angiosperms: n = 320, 40x). Polyploidy and aneuploidy frequently occurring.

Phytochemistry Flavonols (kaempferol, quercetin, myricetin), methylated and non-methylated flavones, acylated flavonol glycosides, cyanidin, red anthocyanins (frequent, also in roots), toxic bufadienolides and similar substances (in Tylecodon, Cotyledon and Kalanchoe), gallic acid, proanthocyanidins (prodelphinidins), non-hydrolyzable tannins, pyrridine alkaloids and other alkaloids, cyanogenic compounds, arbutin, acetophenones, galloylic esters and isocitrate present. Sedoheptulose main reserve sugar. Aluminium accumulated in some species. Ellagic acid and hydrolyzable tannins not found. Cyanogenesis via isoleucine or valine.

Systematics Crassulaceae are sister-group to the clade [Aphanopetalaceae+[Tetracarpaeaceae+[Haloragaceae+Penthoraceae]]].

A possible topology is [Crassuloideae+[Kalanchoideae+Sempervivoideae]].

Crassuloideae Burnett, Outline Bot.: 736, 1092, 1131. Feb 1835 [’Crassulidae’]

2/200–210. Crassula (200–210; almost cosmopolitan), Hypagophytum (1; H. abyssinicum; Ethiopia). – Subcosmopolitan. The Tillaea clade of Crassulais nearly cosmopolitan and the only indigenous clade of Crassulaceae in Australia. Leaves opposite. Leaf margin with hydathodes. Sepals four (or five). Petals four (or five. Stamens four (or five). Anthers somewhat introrse. Carpels three to nine. Median carpel in Tillaea clade abaxial. Ovules tenuinucellar. Parietal tissue absent. Archespore sometimes multicellular. Megasporangial epidermal cells often large. First division of micropylar endosperm cell horizontal. Follicles dehiscing by apical pore. Testal cells often with a single papilla and sinuous anticlinal walls. Tegmen absent. x = 7, 8.

[Kalanchoideae+Sempervivoideae]

Leaf margin usually with only one (sub)apical hydathode. Anthers introrse only in early bud. Placentae sometimes lobed. Parietal tissue present, one to four cell layers thick. First division of micropylar endosperm cell vertical. Seeds costate.

Kalanchoideae A. Berger in Engler et Prantl, Nat. Pflanzenfam., ed. 2, 18a: 383. 3 Mai 1930

4/185–190. Adromischus (c 26; southern Africa), Kalanchoe (c 125; eastern and southern Africa, Madagascar), Tylecodon (c 27; southern Africa), Cotyledon (9; eastern and southern Africa, the Arabian Peninsula). – Africa, Madagascar, the Arabian Peninsula. Shrubs or suffrutices (sometimes small trees). Calciumoxalate present as crystal sand. Petals connate. Anther connective with spherical prolongation. Megasporangial epidermal cells sometimes large. Seeds with four to six costae and micropylar corona. x = 9, 17 (18). Toxic bufadienolides (cardiac glycosides) present.

Sempervivoideae Arn., Botany: 112. 9 Mar 1832 [‘Sempervivae’]

24?/985–1.025. Usually perennial (sometimes annual) herbs, shrubs, or suffrutices. Hylotelephium clade Sinocrassula (7; S. ambigua, S. densirosulata, S. diversifolia, S. indica, S. longistyla, S. techinensis, S. yunnanensis; the Himalayas, southwestern China; incl. Kungia?), Kungia (2; K. aliciae, K. schoenlandii; southern China; in Sinocrassula?), Meterostachys (1; M. sikokianus; southern Korean Peninsula, southern Japan), Orostachys (14; Europe, Central Asia, southern Siberia, Mongolia, China, the Korean Peninsula, Japan), Hylotelephium (c 33; temperate regions on the Northern Hemisphere), Perrierosedum (1; P. madagascariense; Madagascar). – Umbiliceae Meisn., Plant. Vasc. Gen.: Tab. Diagn. 134, Comm. 98. 8-14 Apr 1838. Umbilicus (c 10; Europe, the Mediterranean to Iran, North and East African mountains), Pseudosedum (7; P. acutisepalum, P. affine, P. condensatum, P. koelzii, P. lievenii, P. longidentatum, P. multicaule; Central Asia), Rhodiola (60–65; alpine and mountain areas on the Northern Hemisphere, with their highest diversity in the Himalayas, Tibet and western China), Phedimus (18; Europe, temperate Asia). – Semperviveae Dumort., Fl. Belg.: 85. 1827. Sempervivum (35–40; Europe, the Mediterranean, Morocco, western Asia). – Sedeae Fr., Fl. Scan.: 97. 1835. Aeonium (60–65; Macaronesia, the Mediterranean to Tanzania, the Arabian Peninsula), Pistorinia (4; P. attenuata, P. brachyantha, P. breviflora, P. hispanica; the Iberian Peninsula, Morocco, Algeria), Rosularia (c 30; Europe, the Mediterranean, North Africa, Turkey to Central Asia and the Himalayas), Prometheum (9; Europe, temperate Asia), Sedella (4; S. congdonii, S. leiocarpa, S. pentandra, S. pumila; southern Oregon, California), Dudleya (c 45; southwestern United States, northwestern Mexico), ’Sedum’ (390–400; Europe, Africa, Asia, North to South America; non-monophyletic), Villadia (c 45; Texas, Mexico, Central America, northwestern South America to Peru), Lenophyllum (7; L. acutifolium, L. guttatum, L. latum, L. obtusum, L. reflexum, L. texanum, L. weinbergii; Texas, northeastern Mexico), Graptopetalum (18; Arizona, Mexico), Thompsonella (7; T. colliculosa, T. garcia-mendozae, T. minutiflora, T. mixtecana, T. platyphylla, T. spathulata, T. xochipalensis; Mexico), Echeveria (150–170; southern United States, Mexico, Central America, the Andes, with their highest diversity in Mexico), Pachyphytum (17; Mexico). – Temperate, subtropical and alpine regions on the Northern Hemisphere and southwards to Madagascar and Peru. Leaves usually alternate (spiral; sometimes opposite). Flowers tetramerous to 32-merous. Petals usually free (rarely connate). Carpels three to 32. Megasporangium prolonged, with central vascular bundle. Follicle in Sedum rarely with abaxial dehiscence. Seeds with more than six costae. Micropylar suspensor cell vertically dividing. Suspensor often with compound plasmodesmata. x = 5 or more. Pyrrolidine and piperidine alkaloids often present. Nonhydrolyzable tannins not found. – All species of Echeveria appear to be interfertile. The highly polyphyletic ‘Sedum’ occurs in five of the seven main clades of Sempervivoideae.

Cladogram 1 of Crassulaceae based on DNA sequence (matK) data (Mort & al. 2001).

Cladogram 2 of Crassulaceae pro parte based on DNA (matK) data (Mort & al. 2001).

Distribution The Mediterranean, Turkey, the Arabian Peninsula to Central Asia and Mongolia.

Habit Usually monoecious (or polygamomonoecious?; rarely bisexual), perennial herbs. Achlorophyllous root holoendoparasites on Nitraria, different Cistaceae and Amaranthaceae, Tamarix, and other halophytes.

Vegetative anatomy Mycorrhiza absent. Root modified into fleshy tuberous haustorium, often with host tissue incorporated; small lateral roots with root hairs abundant, arising from rhizome. Phellogen absent. Vascular tissue much reduced. Secondary lateral growth absent. Vessel elements with simple perforation plates; lateral pits? Imperforate tracheary xylem elements? Wood rays absent. Axial parenchyma? Sieve tube plastids Ss type? Calciumoxalate crystals abundant.

Leaves Alternate (spiral), simple, entire, scale-like. Stipules and leaf sheath absent. Venation absent? Stomata anomocytic, rudimentary. Cuticular waxes? Leaf margin entire.

Flowers Actinomorphic, very small. Epigyny. Tepals usually (one to) four or five (to eight), sepaloid, free or connate at base (somewhat more differentiated in male flowers than in female flowers), with ? aestivation. Pistillodial nectary present. Disc absent.

Androecium Stamen single. Filament adnate at base to tepals. Anther dorsifixed, versatile, tetrasporangiate, introrse, longicidal (dehiscing by longitudinal slits). Tapetum secretory. Staminodia absent.

Pollen grains Microsporogenesis simultaneous. Pollen grains tricolporate to tricolporoidate, shed as monads, bicellular at dispersal. Exine semitectate, with columellate infratectum, reticulate.

Gynoecium Pistil probably composed of one carpel (possibly two carpels). Ovary inferior, unilocular (possibly pseudomonomerous). Style single, simple (with two vascular bundles), long, with longitudinal furrow and with conduplicate distal part. Stigma bilobate, type? Male flowers usually with one (sometimes two) yellow hypogynous or epigynous pistillodium (stylodium) modified into nectary.

Ovules Placentation apical. Ovule one per carpel/ovary, orthotropous, pendulous, ategmic to unitegmic, almost crassinucellar. Integument five to seven cell layers thick, or absent. Nucellar cap possibly present? Megagametophyte monosporous, Polygonum type? Endosperm development cellular. Endosperm haustoria? Embryogenesis?

Seeds Aril absent. Seed coat testal. Testa approx. seven cell layers thick, persistent, with little thickened cells. Tegmen absent. Perisperm not developed. Endosperm copious, thick-walled. Embryo small, poorly differentiated, chlorophyll? Cotyledons two. Germination?

Phytochemistry Virtually unknown. Tannins present. Triterpenes with HIV-inhibiting properties (Ma & al. 1999, Nakamura 2004).

Müller Argau in A.-P. de Candolle et A. L. P. P. de Candolle, Prodr. 16(1): 1. med Nov 1869, nom. cons.

Daphniphyllales Pulle ex Cronquist, Integr. Syst. Class. Fl. Pl.: 178. 10 Aug 1981; Daphniphyllanae Takht., Divers. Classif. Fl. Pl.: 140. 24 Apr 1997

Distribution Southwestern India, Sri Lanka, the Himalayas, southern Tibet, Assam, East Asia to Taiwan, the Korean Peninsula and Japan, Southeast Asia, Malesia to New Guinea, Solomon Islands, tropical Australia, with their largest diversity in Yunnan.

Habit Usually dioecious (rarely polygamodioecious), evergreen trees or shrubs. Branches provided with numerous lenticels.

Vegetative anatomy Phellogen? Medulla often septated by diaphragms. Pericyclic fibres absent. Vessel elements with scalariform perforation plates; lateral pits opposite to scalariform, simple and/or bordered pits, non-septate. Imperforate tracheary xylem elements tracheids with bordered pits, non-septate? Wood rays uniseriate or multiseriate, heterocellular. Axial parenchyma apotracheal diffuse or banded. Tyloses common. Sieve tube plastids Ss type, with approx. five globular starch grains. Nodes? Chambered calciumoxalate crystals present in some species.

LeavesUsually alternate (spiral; rarely opposite), simple, entire, with flat ptyxis. Stipules and leaf sheath absent. Petiole vascular bundles? Venation pinnate. Stomata usually paracytic (sometimes anomocytic or laterocytic). Cuticular wax crystalloids as clustered tubuli (Berberis type), chemically dominated by nonacosan-10-ol. Mesophyll with calciumoxalate druses. Leaf margin usually entire.

Flowers Actinomorphic, small. Hypogyny. Sepals two to six, with imbricate aestivation, very small, or absent. Petals absent. Nectary absent. Disc absent.

Androecium Stamens five to 12 (to 24), usually as many as or twice the number of sepals. Filaments short, free from each other and from tepals. Anthers basifixed, non-versatile, tetrasporangiate, latrorse, longicidal (dehiscing by longitudinal valves); connective often somewhat prolonged. Tapetum secretory. Female and male flowers sometimes with staminodia.

Pollen grains Microsporogenesis simultaneous. Pollen grains usually tricolpate (rarely tricolporoidate), shed as monads, bicellular at dispersal. Exine tectate, with columellate infratectum, microperforate, psilate or verrucate.

Gynoecium Pistil composed of usually two (rarely three or four) connate carpels. Ovary superior, incompletely bilocular (rarely trilocular or quadrilocular). Stylodia usually two (rarely three or four), short, recurved or circinate, connate at base. Stigmas relatively massive, decurrent, with multicellular appendages, non-papillate, Dry type. Male flowers sometimes with pistillodium.

Ovules Placentation apical to axile or parietal. Ovules (one or) two per carpel, anatropous, pendulous, epitropous, bitegmic, crassinucellar. Micropyle exostomal, Z-shaped (zig-zag)? Outer integument three to six cell layers thick. Inner integument four or five cell layers thick. Hypostase present. Megagametophyte monosporous, Polygonum type. Synergids with a filiform apparatus. Endosperm development cellular. Endosperm haustoria? Embryogenesis? Polyembryony sometimes occurring.

Fruit A usually one-seeded (rarely two-seeded) drupe, often with persistent stylodia and staminodia.

Seeds Aril absent. Testa persistent, thin-walled, crushed. Exotegmen? Endotegmen with tannins, and thickened and often sclerotized and cutinized cell walls. Perisperm thin, with protein crystals. Endosperm copious, oily and proteinaceous. Embryo small, straight, apical, well differentiated, chlorophyll? Cotyledons two, as wide as radicula. Germination phanerocotylar.

Phytochemistry Flavonols (quercetin, apigenin, luteolin, etc.), Group I carbocyclic iridoids (e.g. asperuloside, daphniphylloside), hydrolyzable tannins, and unique triterpene (squalene) alkaloids of the daphniphylline group (daphniphylline, codaphniphylline etc.) present. Myricetin? Ellagic acid, proanthocyanidins, condensed tannins, and cyanogenic compounds not found. Aluminium accumulated.

de Candolle in de Lamarck et A. P. de Candolle, Fl. Franç., ed. 3, 4(2): 405. 17 Sep 1805 [’Grossulariae’], nom. cons.

Grossulariales DC. ex Bercht. et J. Presl, Přir. Rostlin: 236. Jan-Apr 1820 [‘Grossulariae’]; Ribesiaceae Marquis, Esq. Règne Vég.: 66. 15-22 Jul 1820 [’Ribesioïdeae’]

Distribution Temperate parts of Eurasia, the Mediterranean, northeastern Africa, North America to southern Chile.

Fossils Leaves similar to Ribes are known from Eocene and younger sediments in North America.

Habit Usually bisexual (sometimes dioecious), usually deciduous (rarely evergreen) shrubs, upright, creeping (often with subterranean stems) or occasionally somewhat climbing; branches differentiated into long shoots and short shoots. Leaves sometimes modified into spines.

Vegetative anatomy Phellogen ab initio outer-cortical to pericyclic. Subterranean stems with well developed endodermis. Pericyclic fibres absent. Vessel elements usually with scalariform (rarely simple) perforation plates; lateral pits usually alternate (sometimes scalariform), simple or bordered pits. Imperforate tracheary xylem elements fibre tracheids with simple or bordered pits, septate or non-septate (also vasicentric tracheids). Wood rays uniseriate or multiseriate, homocellular or heterocellular. Axial parenchyma usually absent (rarely apotracheal diffuse or paratracheal scanty or banded). Sieve tube plastids Ss type. Nodes 1:1, unilacunar with one leaf trace, or 3:3, trilacunar with three traces. Tanniniferous cells abundant. Non-lignified stem tissues with numerous cystoliths. Calciumoxalate druses present.

Trichomes Hairs unicellular or multicellular, stalked or unstalked, uniseriate or branched, with or without glandular apex, often peltate-lepidote glandular hairs; epidermal prickles frequent at nodes and internodes.

Leaves Alternate (spiral), simple or almost palmately compound, usually lobed (rarely entire), usually with conduplicate-plicate (rarely convolute) ptyxis. Stipules intrapetiolar, membranous, or absent; leaf sheath absent. Petiole vascular bundle transection arcuate?; petiole bundles connate. Venation palmate. Stomata anomocytic (paracytic?). Cuticular waxes? Domatia abaxial, as pockets. Druses present in parenchyma and collenchyma. Tanniniferous cells numerous. Leaf margin usually coarsely serrate; leaf teeth with hydathodes.

Flowers Actinomorphic, small. Pedicel articulated. Hypanthium present, with basal nectaries. Epigyny or almost epigyny. Sepals usually five (rarely four), with imbricate or subvalvate aestivation, often petaloid, persistent, usually recurved (sometimes connivent into a tube), free. Petals (in reality staminodia?) usually five (rarely four), with open or imbricate aestivation, scale-like to subulate, persistent, free (rarely absent). Nectariferous disc often quinquelobate.

Androecium Stamens usually five (rarely four), antesepalous, alternipetalous. Filaments filiform, inserted on top of hypanthium, free, adnate to sepals (free from petals?). Anthers usually basifixed (sometimes dorsifixed), non-versatile, tetrasporangiate, introrse, longicidal (dehiscing by longitudinal slits); connective sometimes with apical nectary. Tapetum secretory. Female flowers with staminodia.

Pollen grains Microsporogenesis simultaneous. Pollen grains (5–)8–14-pantoporate or zonocolporate (rarely pentacolpodiorate), shed as monads, bicellular at dispersal. Ectoapertures present (rugulate surfaces surrounding endoapertures). Exine pertectate, with columellate? infratectum, rugulate, punctate or spinulate.

Gynoecium Pistil usually composed of two paracarpous, connate and usually median (sometimes transverse) carpels. Ovary inferior or almost inferior, unilocular. Style single, simple or bifid, or stylodia two, free. Stigmas two, capitate, non-papillate, Wet type. Male flowers with pistillodium.

Ovules Placentation parietal (with two somewhat intruding placentae). Ovules four to more than 100 per ovary, anatropous, bitegmic, crassinucellar. Micropyle exostomal. Outer integument three to five cell layers thick, with tanniniferous outer epidermal cells. Inner integument two or three cell layers thick. Funicular obturator present. Parietal tissue three or four cell layers thick. Hypostase present. Megagametophyte monosporous, Polygonum type. Endosperm development usually cellular (sometimes helobial or nuclear?). Endosperm haustorium chalazal. Embryogenesis irregular.

Fruit A many-seeded berry-like fruit with persistent perianth and staminal remnants.

Seeds Funicular aril surrounding entire or parts of seed. Seed coat endotestal. Exotesta mucilaginous (myxotesta); exotestal cells palisade, large with thin walls; epidermal cells large and pulpy. Endotesta hard; endotestal cells small, cuboid, with calciumoxalate crystals, and with radial and inner walls lignified. Tegmic cells elongate, tanniniferous. Perisperm not developed. Endosperm copious, oily, proteinaceous and with hemicellulose, with somewhat thickened walls. Embryo small, straight, well differentiated, without chlorophyll. Cotyledons two, with main vein ending in hydathodal tooth. Germination phanerocotylar.

Phytochemistry Flavonols (kaempferol, quercetin, myricetin), cyanidin, delphinidin, mono- and sesquiterpenes, ellagic acid, ellagitannins, and tyrosine-derived cyanogenic compounds present. Iridoids not found. Aluminium accumulated in some species.

Use Ornamental plants, fruits, tea (leaves from Ribes nigrum), medicinal plants.

Brown in M. Flinders, Voy. Terra Austral. 2: 549. 19 Jul 1814 [’Halorageae’], nom. cons.

Cercodiaceae Juss. in F. Cuvier, Dict. Sci. Nat. 7: 441. 24 Mai 1817 [‘Cercodianae’]; Haloragales Link, Handbuch 2: 52. 4-11 Jul 1829 [’Halorageae’]; Myriophyllaceae Schultz Sch., Nat. Syst. Pflanzenr.: 324. 30 Jan-10 Feb 1832 [’Myriophylleae’]; Haloragineae Engl., Syllabus, ed. 2: 162. Mai 1898 [‘Halorrhagidineae’]

Distribution Largest diversity on the Southern Hemisphere, particularly in Australia; Myriophyllum cosmopolitan; Proserpinaca in North America and the West Indies.

Fossils Obispocaulis myriophylloides and Tarahumara sophiae from the Campanian to the Maastrichtian of Mexico have both been assigned to either Haloragaceae or very close to that clade. Tarahumara had unisexual epigynous flowers with four basally connate uniovulate carpels, and a drupaceous fruit. Obispocaulis is represented by fossil stems containing aerenchyma and bearing adpressed leaves. Cenozoic pollen and fruits of Haloragaceae are frequent in both the Northern and Southern Hemispheres. Fossils of Proserpinaca are known from pre-Pliocene layers in Europe.

Habit Usually monoecious or polygamomonoecious (rarely bisexual or dioecious), perennial or annual herbs, suffrutices or evergreen small shrubs (‘Haloragodendron’ consists of shrubs and small trees). Numerous species are aquatic, other representatives are amphibious, hygrophytes or terrestrial mesophytes. Myriophyllum in the Northern Hemisphere produces turions (condensed reproductive and hibernating shoots). The main root in aquatic and amphibious species is replaced by adventitious roots (without root hairs), anchoring the plant to the substrate (adventitious roots in Haloragis inserted between the leaves).

Vegetative anatomy Phellogen? Primary cortex with numerous aerial cavities (especially in aquatic species). Primary vascular tissue strongly reduced in aquatic species. Endodermis significant especially in aquatic species. Secondary lateral growth normal or absent. Vessel elements with simple perforation plates; lateral pits? Imperforate tracheary xylem elements ?, with simple pits (Glischrocaryon). Wood rays uniseriate or multiseriate, homocellular or heterocellular. Axial parenchyma? Sieve tube plastids Ss type. Nodes 1:1, unilacunar with one leaf trace. Calciumoxalate crystals often present in hair-shaped cortical cells.

Trichomes Hairs unicellular or multicellular, uniseriate, often with silica, or absent.

Leaves Usually opposite or verticillate (sometimes alternate, spiral), simple or compound (often pinnately compound), entire or often finely lobed, with conduplicate-flat ptyxis (in Myriophyllum and Proserpinaca heterophylly). Stipules very small or absent; leaf sheath absent. Colleters present? Petiole vascular bundle transection arcuate? Venation pinnate (or leaves one-veined). Stomata usually anomocytic (often absent). Cuticular wax crystalloids usually absent (rarely as parallel grouped platelets, Hypericum type). Leaf margin serrate or entire, eglandular.

Inflorescence Terminal or axillary, thyrso-paniculate, thyrsoid, fasciculate etc., or raceme- or spike-like, or flowers solitary, axillary. Floral prophylls (bracteoles) present or absent.

Flowers Actinomorphic, small. Epigyny. Sepals usually four (in Proserpinaca three, rarely two), with valvate aestivation, persistent (absent in female flowers of Myriophyllum). Petals usually four (in Proserpinaca three, rarely two), with imbricate aestivation, caducous (usually absent in Proserpinaca and female flowers in Myriophyllum and Laurembergia). Nectary absent. Disc absent.

Androecium Stamens usually (two to) four or 4+4, as many as or twice the number of sepals (when four then antesepalous). Filaments short, narrow, free from each other and from tepals. Anthers basifixed, non-versatile, tetrasporangiate, introrse, longicidal (dehiscing by longitudinal slits); connective sometimes slightly prolonged. Tapetum secretory. Antesepalous staminodia present in some species of Gonocarpus.

Pollen grains Microsporogenesis simultaneous. Pollen grains 4–6(–20)-colpate or 4–6(–20)-porate, shed as monads, usually tricellular (rarely bicellular) at dispersal. Exine tectate, with columellate infratectum, microperforate and beset with small supratectal processes.

Gynoecium Pistil composed of usually four (rarely two or three) connate carpels; carpels antepetalous or median carpel adaxial. Ovary inferior, (unilocular to) quadrilocular (septa sometimes poorly developed, absent in Laurembergia and most species of Glischrocaryon). Stylodia separate, clavate, somewhat swollen at base (sometimes absent). Stigmas capitate or penicillate, papillate, Dry type. Pistillodium?

Ovules Placentation apical. Ovules one or two (one aborting) per carpel, anatropous or hemianatropous, pendulous, usually apotropous (sometimes epitropous), bitegmic, crassinucellar (or tenuinucellar?). Micropyle endostomal (Myriophyllum). Outer integument two or three cell layers thick. Inner integument approx. two cell layers thick. Parietal tissue two or three cell layers thick. Archesporial cell hypodermal (Myriophyllum). Funicular obturator poorly developed or absent. Hypostase often present. Nucellar cap often present. Megagametophyte monosporous, Polygonum type. Synergids with a filiform apparatus. Antipodal cells persistent. Endosperm development usually cellular (in Laurembergia and some species of Myriophyllum nuclear). Haustorial suspensor present. Endosperm haustoria? Embryogenesis caryophyllad.

Fruit A one- to four-seeded nut (in Proserpinaca three-seeded), a drupe with one- to four-seeded pyrene (in Meziella) or a schizocarp with two to four nut-like mericarps (in Myriophyllum).

Seeds Aril absent. Seed coat exotestal. Exotesta (sometimes also hypodermal layer) persistent, with thin-walled cells; other parts of testa and tegmen degrading and crushed. Perisperm not developed. Endosperm usually copious, starchy, oily. Embryo usually large, straight, without chlorophyll. Cotyledons two. Germination phanerocotylar.

Phytochemistry Flavones, pelargonidin (in leaves), cyanidin, ellagic and gallic acid, tannins, myriophyllin (in hair glands of Myriophyllum), cyanogenic compounds, saponins, and coumaric acid present. Flavonols (kaempferol, quercetin)?

Systematics Glischrocaryon (5; G. angustifolium, G. aureum, G. behrii, G. flavescens, G. roei; southern Western Australia, southern South Australia, New South Wales, Victoria; incl. Haloragodendron?), ‘Haloragodendron’ (5–6; H. baeuerlenii, H. gibsonii, H. glandulosum, H. lucasii, H. monospermum, H. racemosum; southwestern Western Australia, southeastern New South Wales, eastern Victoria, Tasmania; paraphyletic; in Glischrocaryon?); Proserpinaca (4; P. amblygona, P. intermedia, P. palustris, P. pectinata; southeastern United States, the West Indies), Meionectes (2; M. brownii, M. preissii; southwestern Western Australia, southeastern South Australia, southern Victoria, Tasmania), Trihaloragis (1; T. hexandra; southwestern Western Australia), Haloragis (17?; Australia, New Caledonia, New Zealand, Rapa Island, Juan Fernández), Gonocarpus (c 40; Southeast Asia and Malesia to Japan, Australia and New Zealand), Laurembergia (4; L. minor, L. repens, L. tetrandra, L. veronicifolia; tropical and subtropical regions on both hemispheres), Myriophyllum (c 70; cosmopolitan, with their highest diversity in Australia).

Haloragaceae are sister-group to Penthorum (Penthoraceae).

The Haloragodendron clade (probably including Glischrocaryon) is sister to the remaining Haloragaceae. The crown clade is not completely resolved, since Proserpinaca and Meionectes are parts of a basal trichotomy together with the remainder.

Majority rule consensus tree (simplified) from Bayesian analysis of Haloragaceae based on DNA sequence data (Moody & Les 2007).

Brown in C. Abel, Narr. Journey China: 374. 15 Aug 1818 [‘Hamamelideae’], nom. cons.

Fothergillaceae Nutt., Gen. N. Amer. Pl. 1: 108. 14 Jul 1818 [‘Fothergilleae’]; Fothergillales Link, Handbuch 2: 445. 4-11 Jul 1829 [’Fothergilleae’]; Hamamelidales Link, Handbuch 2: 4. 4-11 Jul 1829 [’Hamamelideae’]; Parrotiaceae Horan., Prim. Lin. Syst. Nat.: 79. 2 Nov 1834 [‘Parrotiaceae (Hamamelideae)’]; Hamamelidopsida Brongn., Enum. Plant. Mus. Paris: xxix, 109. 12 Aug 1843 [’Hamamelineae’]; Bucklandiaceae J. Agardh, Theoria Syst. Plant.: 155. Apr-Sep 1858 [’Bucklandieae’], nom. illeg.; Disanthaceae Nakai, Chosakuronbun Mokuroku [Ord. Fam. Trib. Nov.]: 246. 20 Jul 1943; Rhodoleiaceae Nakai, Chosakuronbun Mokuroku [Ord. Fam. Trib. Nov.]: 246. 20 Jul 1943; Exbucklandiaceae Reveal et Doweld in Novon 9: 552. 30 Dec 1999; Hamamelidineae Thorne et Reveal in Bot. Rev. (Lancaster) 73: 91. 29 Jun 2007

Distribution Eastern and southern Africa, Madagascar, southern Turkey, southeastern Trans-Caucasus, northern Iran, western and eastern Himalayas, Assam, Manipure, East and Southeast Asia to the Korean Peninsula and Japan, Malesia to New Guinea, northeastern Australia (Queensland), eastern North America, Central America, northeastern South America.

Fossils Allonia decandra from the Late Santonian of Georgia (the United States) is a pentamerous male flower with connate sepals and two staminal whorls, tricolpate pollen having reticulate exine and columellate infratectum, and with an adaxial lobate (nectariferous?) disc. Allonia seems to be sister-group to Maingaya. Androdecidua endressii is another pentamerous staminate flower from the Late Santonian of Georgia. Numerous fossils (especially leaves and seeds) of Hamamelidaceae are known from the Cenozoic. Seeds and bilocular fruits of Rhodoleia have been found in Maastrichtian to Miocene layers in Europe.

Habit Usually bisexual (sometimes monoecious, andromonoecious or polygamomonoecious), evergreen or deciduous trees or shrubs.

Vegetative anatomy Phellogen ab initio superficial. Primary vascular tissues as a cylinder, without separate bundles. Vessel elements with usually scalariform (sometimes reticulate) perforation plates; lateral pits usually opposite to scalariform (rarely alternate), simple pits. Vestured pits sometimes present. Imperforate tracheary xylem elements tracheids or fibre tracheids with bordered pits, non-septate. Wood rays uniseriate or multiseriate, homocellular or heterocellular. Axial parenchyma apotracheal diffuse or diffuse-in-aggregates, or paratracheal scanty (or unilateral), or absent. Tyloses sometimes abundant. Sieve tube plastids Ss type, with five (to ten) starch grains. Nodes usually 3:3, trilacunar with three leaf traces (in Chunia and Mytilaria 5:5, pentalacunar with five traces). Medulla in Mytilaria with resiniferous secretory canals. Branched sclereids frequent. Some species possess secretory canals. Parenchyma usually with prismatic calciumoxalate crystals.

Trichomes Hairs usually multicellular (sometimes unicellular), often early sclerified, usually stellate or tufted (sometimes uniseriate).

Leaves Usually alternate (usually distichous, sometimes spiral; rarely opposite), simple, entire, with conduplicate-flat or conduplicate-plicate ptyxis. Stipules usually caducous (sometimes cauline); leaf sheath absent. Petiole vascular bundle transection usually annular (rarely arcuate; petiole sometimes with adaxial bundle). Venation usually palmate or with stout veins at base (rarely pinnate), eucamptodromous or actinodromous and brochidodromous or craspedodromous. Stomata usually paracytic (sometimes laterocytic), often only on adaxial side of lamina. Cuticular wax crystalloids usually absent (rarely as irregular platelets, or as clustered tubuli of Berberis type, chemically dominated by nonacosan-10-ol). Domatia rarely present. Epidermis with or without mucilage cells. Mesophyll with calciumoxalate crystals and usually sclerenchymatous idioblasts with sclereids of different appearance (brachysclereids, columnar, etc.). Leaf margin usually serrate (rarely entire); leaf teeth often fothergilloid (with transparent glandular apex; gland often absent).

Inflorescence Terminal or axillary, thyrse, botryoid, panicle, spike-, catkin- or head-like (rarely raceme; in Rhodoleia pendant capitulate pseudanthium with involucre consisting of bracts).

Flowers Usually actinomorphic. Hypanthium present or absent. Usually epigyny (rarely hypogyny). Sepals (two to) four or five (to seven), usually with imbricate aestivation, usually free (rarely connate), often persistent (rarely absent). Petals (two to) four or five, with open or valvate (or imbricate) aestivation, adaxially circinate, usually band-like, often spirally twisted, sometimes stipitate, caducous, free (rarely absent). Nectaries as an intrastaminal annular nectariferous disc or staminodial nectaries (in Hamamelis), at petal bases (in Disanthus) or as nectariferous glands around filament (in Rhodoleia).

Androecium Stamens (one to) four or five (to 24), in one or two whorls, often as many as sepals, antesepalous. Filaments free from each other and from tepals. Anthers usually basifixed, non-versatile, usually tetrasporangiate (rarely disporangiate), latrorse or introrse, longicidal (usually dehiscing by one or two valves or slits; rarely by basal pore); connective usually more or less prolonged. Tapetum secretory, with uni-, bi- or multinucleate cells. Staminodia antepetalous, sometimes alternating with fertile stamens, or absent.

Pollen grains Microsporogenesis simultaneous. Pollen grains usually tricolpate (rarely tetracolpate, pantocolpate, hexarugate,polyrugate or polyforate), shed as monads, bicellular at dispersal. Exine semitectate, with columellate infratectum, reticulate.

Gynoecium Pistil composed of usually two (rarely three) partially or entirely connate carpels. Ovary usually inferior (rarely superior), usually bilocular (rarely trilocular). Stylodia usually two (rarely three), long, free or connate below. Stigmas terminal or decurrent, with multicellular appendages, non-papillate, Dry type. Male flowers often with pistillodium.

Ovules Placentation axile to apical. Ovule usually one or several (rarely numerous) per carpel, anatropous, usually pendulous (along carpellary edges when numerous), apotropous to epitropous (half epitropous, half apotropous), bitegmic, crassinucellar. Micropyle endostomal or bistomal, sometimes Z-shaped (zig-zag). Outer integument usually six to twelve (rarely two) cell layers thick. Inner integument two or three cell layers thick. Hypostase present. Parietal tissue usually eight to ten cell layers thick. Nucellar cap sometimes two cell layers thick. Archespore usually unicellular (rarely multicellular). Megagametophyte monosporous, Polygonum type. Endosperm development usually nuclear (at least in Parrotiopsis cellular). Endosperm haustoria? Embryogenesis chenopodiad (Distylium, Hamamelis) or solanad (Parrotiopsis).

Fruit A loculicidal and/or septicidal double-walled capsule with coriaceous or lignified exocarp and lignified or corneous endocarp, often with persistent calyx (in Rhodoleia a syncarp with capsular unities).

Seeds Aril absent. Hilum large. Seed coat (meso)testal. Testa usually thick, hard, multiplicative, shining and often two-coloured, winged or unwinged. Exotestal cells usually thickened. Mesotesta massive, usually consisting of sclerotized fibrous cells. Tegmen not included in mature seed coat; tegmic cells tanniniferus. Perisperm more or less developed. Endosperm usually sparse, oily. Embryo straight, usually small, well differentiated. Cotyledons two. Germination phanerocotylar. Polyembryony sometimes occurring.

Phytochemistry Flavonols (kaempferol, quercetin, myricetin), flavone-C-glycosides, cyanidin, delphinidin, ellagic acid, and tannins present. Chalcones, alkaloids, and cyanogenic compounds not found.

Use Ornamental plants, medicinal plants (also healing substances etc. from Hamamelis virginiana), timber.

Systematics Hamamelidaceae are sister-group to the clade [Cercidiphyllaceae+Daphniphyllaceae].

Exbucklandioideae are sister to the remainder.

Exbucklandioideae (A. Reinsch) H. T. Chang in Acta Sci. Nat. Univ. Sunyatseni 1973(1): 54. Nov 1973

3/10. Exbucklandia (3; E. longipetala, E. populnea, E. tonkinensis; Assam, eastern Himalayas, southern China, the Malay Peninsula, Sumatra), Rhodoleia (6; R. championii, R. forrestii, R. henryi, R. macrocarpa, R. parvipetala, R. stenopetala; southern China, Southeast Asia to Sumatra), Mytilaria (1; M. laosensis; Guangxi, Laos). – Assam to Southeast Asia and southern China, West Malesia. Inflorescence usually capitate. Epigyny or half epigyny. Petals sometimes absent. Micropyle in Exbucklandia with partially prolonged outer integument. Outer integument in Exbucklandia two cell layers thick. Seed coat in Exbucklandia and Rhodoleia winged. Only exotestal cells thickened. n = 8, 12.

[Disanthoideae+Hamamelidoideae]

Disanthoideae Harms in Engler et Prantl, Nat. Pflanzenfam., ed. 2, 18a: 314. 3 Mai 1930

1/1. Disanthus (1; D. cercidifolius; Japan). – Hypogyny. Nectaries present at petal bases. Anthers dehiscing with longitudinal slits. n = 8.

Hamamelidoideae Burnett, Outlines Bot.: 733, 1132. Feb 1835 [‘Hamamelidae’]

22/99–100. Chunia (1; C. bucklandioides; Hainan), Corylopsis (c 25; eastern Himalayas, China, the Korean Peninsula, Japan), Dicoryphe (13; Madagascar, the Comoros), Distyliopsis (6; D. dunnii, D. lanata, D. laurifolia, D. salicifolia, D. tutcheri, D. yunnanensis; Burma, Thailand, Indochina, Malesia, Taiwan), Distylium (c 15; Southeast Asia, Malesia), Embolanthera (2; E. glabrescens, E. spicata; Southeast Asia, the Philippines), Eustigma (3; E. balansae, E. lenticellatum, E. oblongifolium; southern China, Southeast Asia), Fortunearia (1; F. sinensis; central and eastern China), Fothergilla (2–3; F. gardenia, F. major, F. monticola; southeastern United States), Hamamelis (6; H. mexicana, H. ovalis, H. vernalis, H. virginiana: southeastern Canada, eastern United States, Mexico; H. mollis: China; H. japonica: Japan), Loropetalum (3; L. chinense, L. lanceum, L. subcordatum; northern and northeastern India to China, Japan), Maingaya (1; M. malayana; Penang and Perak on the Malay Peninsula), Matudaea (2; M. colombiana, M. trinervia; central Mexico to Honduras), Molinadendron (3; M. guatemalense, M. hondurense, M. sinaloense; Mexico, Central America), Neostrearia (1; N. fleckeri; northeastern Queensland), Noahdendron (1; N. nicholasii; northeastern Queensland), Ostrearia (1; O. australiana; northeastern Queensland), Parrotia (2; P. persica: southwestern Caspian area; P. subaequalis: eastern China), Parrotiopsis (2; P. involucrata, P. jacquemontiana; the Himalayas), Sinowilsonia (1; S. henryi; western and central China), Sycopsis (2; S. sinensis, S. triplinervia; Assam, China, Taiwan), Trichocladus (6; T. crinitus, T. dentatus, T. ecklonianus, T. ellipticus, T. goetzei, T. grandiflorus; tropical and southern Africa). – Distribution as for Hamamelidaceae. Leaves with craspedodromous venation. Sepals usually absent (sometimes five to nine). Petals usually absent. Stamens four to 24. Anthers dehiscing by valves. Ovule one (in reality three, two of which sterile) per carpel, usually more or less epitropous (sometimes apotropous). Fruit with ballistic seed dispersal. n = 12. – Corylopsideae Harms in H. G. A. Engler et K. A. E. Prantl, Nat. Pflanzenfam., ed. 2, 18a: 325. 3 Mai 1930 are sister to a clade consisting of Eustigmateae Harms in H. G. A. Engler et K. A. E. Prantl, Nat. Pflanzenfam., ed. 2, 18a: 314. 3 Mai 1930 and Hamamelideae DC., Prodr. 4: 268. late Sep 1830 [‘Hamameleae’] (Li & al. 1999).

Cladogram of Hamamelidaceae based on DNA (nuclear ITS) sequence data (Li & al. 1999).

Distribution Eastern and southern Africa, eastern Himalayas to the Korean Peninsula, Japan, Taiwan, Southeast Asia, West Malesia, southeastern United States.

Fossils Iteaceae fossils – mostly diporate pollen grains, but also leaves, fruits and seeds – have been described from the Eocene to the Pliocene of Europe. Ademanthemum iteoides, a flower fossilized in Baltic amber, may be assigned to Iteaceae. Fossil pollen grains of ’Choristylis’ (Itea) are known from Europe and leaves similar to those in Itea have been found in Eocene and younger layers in western North America.

Habit Bisexual or polygamomonoecious, evergreen or deciduous trees or shrubs (rarely climbing).

Vegetative anatomy Phellogen superficial. Young stem with separate vascular bundles. Medulla septated (by diaphragms?). Vessel elements with scalariform perforation plates; lateral pits opposite to scalariform, bordered pits. Imperforate tracheary xylem elements ? with bordered pits, non-septate. Wood rays uniseriate or multiseriate, heterocellular. Axial parenchyma apotracheal diffuse or diffuse-in-aggregates (sometimes absent). Sieve tube plastids Ss type. Nodes 3:3, trilacunar with three leaf traces. Calciumoxalate druses present in cortex and medulla.

Leaves Alternate (spiral), simple, entire, sometimes coriaceous, with conduplicate ptyxis. Stipules small, subulate, inserted at petiole base or stem, or absent; leaf sheath absent. Petiole vascular bundle transection arcuate? Venation pinnate. Stomata anomocytic (paracytic?). Cuticular wax crystalloids? Leaf margin usually glandular-serrate (rarely entire; in Itea ilicifolia spinose-dentate).

Flowers Actinomorphic, small. Hypanthium present. Hypogyny to epigyny. Sepals five, with open or valvate aestivation, persistent, connate at base into tube. Petals five, with valvate aestivation, persistent, free. Nectariferous disc intrastaminal, annular, on hypanthium rim.

Androecium Stamens five, antesepalous, alternipetalous. Filaments subulate, inserted at margin of nectariferous disc, free from each other and from tepals. Anthers dorsifixed, non-versatile, tetrasporangiate, introrse, longicidal (dehiscing by longitudinal slits); connective slightly prolonged. Tapetum secretory. Staminodia absent.

Pollen grains Microsporogenesis simultaneous. Pollen grains bilateral/heteropolar, usually diporate (rarely triporate), shed as monads, bicellular at dispersal. Exine tectate, with granular infratectum, psilate to scabrate.

Gynoecium Pistil composed of two ab initio free, finally connate carpels. Ovary superior to almost inferior, bilocular. Style single, simple or bifid, at anthesis with connivent stylodia. Stigma capitate or lobate, at anthesis with connivent (often connate) and in fruit separate lobes, non-papillate?, Wet type. Pistillodium absent.

Ovules Placentation axile. Ovules four to c. 50 per carpel, usually bitegmic (in ’Choristylis’ unitegmic), crassinucellar. Micropyle bistomal?, not Z-shaped. Outer integument ? cell layers thick. Inner integument ? cell layers thick. Parietal tissue three (to seven) cell layers thick. Megagametophyte monosporous, Polygonum type. Endosperm development? Endosperm haustoria? Embryogenesis?

Fruit A septicidal capsule with persistent perianth (valves often connate in stigmatic region).

Seeds Aril absent. Seed coat exotestal. Exotestal cells tanniniferous, with thickened outer walls. Mesotesta and endotesta crushed. Tegmen? Perisperm not developed. Endosperm sparse, with lipids and aleuron. Embryo large, curved, well differentiated, chlorophyll? Cotyledons two. Germination?

Phytochemistry Flavone-C-glycosides, proanthocyanidins (prodelphinidins), tyrosine-derived cyanogenic compounds, and allitol present. Flavonols and ellagic acid not found.

Medusandrales F. Novák ex Takht., Divers. Classif. Fl. Pl.: 353. 24 Apr 1997

Vegetative anatomy Phellogen ab initio superficial. Vessel elements very long, with scalariform perforation plates (with numerous transverse ridges); lateral pits scalariform or opposite, bordered pits. Imperforate tracheary xylem elements fibre tracheids with bordered pits, non-septate? Wood rays usually uniseriate, heterocellular. Axial parenchyma usually paratracheal scanty, or diffuse. Sieve element plastids S type. Nodes? Laticifers present in outer part of medulla, with lemon-coloured latex. Some phloem cells with aggregated crystals.

Leaves Alternate (spiral), simple (unifoliolate?), entire, with ? ptyxis. Stipules cauline, small, early caducous; leaf sheath absent. Petiole apex with pulvinus having complex anatomy. Petiole vascular bundle transection annular; petiole with medullary annular bundle. Venation palmate, with two sides of base converging in apical part of distally swollen petiole (veins arising from base or near base); secondary veins numerous, parallel. Stomata anomocytic. Cuticular wax crystalloids? Leaf margin crenate to weakly serrate.

Flowers Actinomorphic, small. Hypogyny. Sepals five, with apert, open (valvate?) aestivation, persistent, accrescent, free or connate at base. Petals five, with imbricate aestivation, free. Nectary absent. Disc absent.

Androecium Stamens five, antepetalous. Filaments free, glabrous, free from petals or adnate (epipetalous) at least near base. Anthers dorsifixed, non-versatile, tetrasporangiate, latrorse, valvate (dehiscing by longitudinal recurved valves). Tapetum? Staminodia five, antesepalous, very long (filaments much longer than petals), densely pubescent with clavate hairs, apically with aborted anther reduced to quadrilobate outgrowth.

Pollen grains Microsporogenesis simultaneous? Pollen grains (2–)3-colpor(oid)ate, shed as monads, ?-celled at dispersal. Exine semitectate, infratectum columellate, reticulate.

Gynoecium Pistil composed of usually three (sometimes four) connate carpels. Ovary superior, unilocular, with central column free except at base and apex. Stylodia usually three (sometimes four), separate. Stigma punctate, non-papillate, type? Pistillodium absent.

Ovules Placentation free central-apical. Ovules two per carpel, anatropous, pendulous, epitropous, bitegmic?, crassinucellar? Micropyle ?-stomal. Outer integument ? cell layers thick. Inner integument ? cell layers thick. Megagametophyte monosporous?, Polygonum type? Endosperm development? Endosperm haustoria? Embryogenesis?

Fruit A single-seeded leathery capsule with persistent, accrescent and strongly recurved sepals.

Seeds Aril absent. Seed coat testal. Testal cells thin-walled. Exotestal cells? Endotesta? Tegmen crushed? Perisperm not developed. Endosperm copious, somewhat ruminate. Embryo minute, straight, chlorophyll? Cotyledons two. Germination?

DNA Insertion of a single base (adenosine) in 18S rDNA (synapomorphy of Saxifragales).

Paeoniineae Mart., Consp. Regn. Veg.: 40. Sep-Oct 1835 [‘Paeoniaceae’]; Paeoniales Heintze, Cormofyt. Fylog.: 12, 97. 1927; Paeonianae Doweld, Tent. Syst. Plant. Vasc.: xxvii. 23 Dec 2001; Paeoniidae C. Y. Wu in Acta Phytotaxon. Sin. 40: 302. 2002

Distribution South and Southeast Europe, the Mediterranean, subtropical, temperate and subarctic parts of Asia, western North America.

Fossils Uncertain. Paeoniaecarpum hungaricum are fossil fruits from the Miocene of Hungary, which have sometimes been assigned to Paeoniaceae.

Habit Bisexual, perennial herbs, often with root or rhizome tubers, or suffrutices (rarely deciduous shrubs).

Vegetative anatomy Phellogen ab initio inner-cortical. Cortical vascular bundles present. Vessel elements usually with scalariform (sometimes reticulate or simple) perforation plates; lateral pits alternate or transitional (rarely scalariform). Imperforate tracheary xylem elements tracheids with bordered pits, non-septate? Wood rays uniseriate or multiseriate, homocellular or heterocellular (with lignified cell walls). Axial parenchyma apotracheal (some cells among fibres) or paratracheal scanty. Sieve tube plastids Ss type. Nodes 3:3, trilacunar with three leaf traces, or 5:5, pentalacunar with five traces. Calciumoxalate crystals (druses etc.) present.

Leaves Alternate (spiral), pinnately compound (sometimes twice or several timespinnately compound) or palmately compound to ternate or simple, lobed, with ? ptyxis. Stipules and leaf sheath absent. Petiole vascular bundle transection annular. Venation palmate. Stomata anomocytic. Cuticular wax crystalloids as transversely ridged rodlets (Aristolochia type), chemically dominated by palmitone (hentriacontan-16-one). Mesophyll with calciumoxalate druses. Leaf margin serrate.

Inflorescence Flowers terminal, usually solitary (sometimes few together in cymose inflorescences). Extrafloral nectaries frequent on bracts enclosing floral buds.

Flowers Actinomorphic, large. Hypogyny. Sepals (three to) five (to seven), with imbricate aestivation, spiral, coriaceous, persistent, free, intergrading into petals. Petals five to eight (to 13), with imbricate aestivation, spiral, caducous, free. Nectariferous disc intrastaminal, annular or lobate, fleshy (developed from receptacle or stamens).

Androecium Stamens c. 50 to more than 150, spiral, initiated from five primordia, centrifugally developing and continuing spiral corolla phyllotaxis. Filaments narrow, more or less connivent in five fascicles (staminal vascular strands five, branched). Anthers basifixed, non-versatile, tetrasporangiate, extrorse, longicidal (dehiscing by longitudinal slits). Tapetum secretory. Staminodia modified into intrastaminal glands or absent.

Pollen grains Microsporogenesis simultaneous. Pollen grains tricolp(oroid)ate, shed as monads, bicellular at dispersal. Exine tectate to semitectate, with columellate infratectum, perforate reticulate, punctate, rugulate, foveolate, or irregularly tuberculate-foveolate.

Gynoecium Carpels (two or) three to eight (to 15), spiral (secondarily), free (secondarily), arcuately diverging. Ovary superior, unilocular (apocarpy). Style very short or absent. Stigma expanded, oblique, papillate, Wet type. Pistillodium absent.

Ovules Placentation marginal (ovules biseriate, inserted on placental outgrowths, and richly vascularized). Ovules approx. ten to more than 100 per carpel, anatropous, bitegmic, crassinucellar (megasporangium degenerating after fertilization or prior to anthesis). Micropyle exostomal to bistomal. Outer integument c. 10 to c. 20 cell layers thick, two-layered. Inner integument three or four cell layers thick. Hypostase present. Parietal tissue approx. five cell layers thick. Nucellar cap massive, approx. twelve cell layers thick. Megasporangium usually absorbed prior to anthesis. Archespore often multicellular (often several germinating). Megagametophyte monosporous, Polygonum type. Synergids with a filiform apparatus. Endosperm development ab initio nuclear. Endosperm haustorium chalazal. Embryogenesis unique among angiosperms, including asymmetrical first division of zygote, degeneration of smaller daughter cell, and free nuclear divisions in larger cell; this resulting in nuclear stage (coenocytic proembryo), from which one or usually several embryos are formed through budding; cell walls produced six or seven (sometimes eight) free nuclear divisions later; only a single embryo maturing.

Seeds Seed large, usually with small fleshy funicular aril. Seed coat mesotestal. Testa a fleshy sarcotesta, vascularized, ab initio red, later black, glossy; in some species developed black fertilized seeds as well as undeveloped showy red unfertilized seeds present. Exotestal cells palisade, thickened. Hypodermis palisade, lignified. Mesotesta sometimes thickened. Endotesta crushed. Tegmen absent. Perisperm not developed. Endosperm copious, oily, with amyloid (xyloglucans). Embryo very small, well differentiated, without chlorophyll. Cotyledons two. Germination phanerocotylar or cryptocotylar.

DNA Plastid gene infA defunct (pseudogene present). Mitochondrial intron coxII.i3 lost.

Phytochemistry Flavonols (kaempferol, quercetin etc.), flavones, Group I carbocyclic iridoids, oleanolic acid derivatives, phenolic substances and glycosides (e.g. paeonol, paeonolide, paeonoside, paeoniflorin, oxypaeoniflorin, benzoylpaeoniflorin, and alliflorin), acetophenones, amids and ethereal oils present. Alkaloids? Ellagic acid, proanthocyanidins, tannins, saponins, and cyanogenic compounds not found.

Distribution Northeastern Asia, China, the Korean Peninsula, Japan, northern Vietnam, eastern United States.

Vegetative anatomy Phellogen (in root) ab inition superficial. Cortex consisting of outer exodermis and inner aerenchyma. Endodermis? Pericyclic fibres absent. Pseudosiphonostele present in young stems. Secondary lateral growth normal or absent. Vessel elements with scalariform perforation plates; lateral pits?, bordered pits. Imperforate tracheary xylem elements fibre tracheids and tracheids with bordered pits, non-septate (also vasicentric tracheids). Wood rays usually uniseriate or biseriate, homocellular. Axial parenchyma absent. Sieve tube plastids Ss type, with starch, but without protein inclusions. Nodes 1:1, unilacunar with one leaf trace. Crystals?

Trichomes Hairs (in Penthorum sedoides) multicellular, triseriate or quadriseriate, glandular, or absent (in P. chinense).

Leaves Alternate (spiral), simple, entire, with supervolute ptyxis. Stipules and leaf sheath absent. Colleters present. Petiole vascular bundle transection arcuate. Venation pinnate, brochidodromous, with distinct mid-vein. Stomata anomocytic. Cuticular wax crystalloids? Leaf margin glandular serrate; teeth often with apical hydathode.

Inflorescence Terminal or axillary, usually scorpioid monochasium. Bracts lateral, perpendicular to pedicel.

Flowers Actinomorphic. Ab initio epigyny (half epigyny with ovary somewhat sunken into receptacle), later hypogyny. Hypanthium present. Sepals five (to eight), with valvate aestivation, unequal, persistent, connate at base. Petals usually absent (sometimes one to eight, small, free, usually shorter than sepals). Nectary absent. Disc absent.

Androecium Stamens 5+5 (to 8+8), twice as many as sepals. Filaments filiform, free from each other and from tepals. Anthers basifixed, non-versatile, disporangiate, latrorse, longicidal (dehiscing by longitudinal slits). Tapetum secretory. Staminodia five (to eight).

Pollen grains Microsporogenesis simultaneous. Pollen grains tricolporate(or tricolporoidate), shed as monads, ?-cellular at dispersal. Exine tectate, with columellate? infratectum, perforate or microreticulate.

Gynoecium Pistil composed of five (to eight) antesepalous carpels, free or connate at base. Ovary ab initio inferior (semi-inferior) and later superior, unilocular (apocarpy) or multilocular in proximal part. Stylodia five (to eight), short, submarginal. Stigmas small, capitate, type? Pistillodium absent.

Ovules Placentation apical-axile, later intrusive. Ovules numerous per carpel, anatropous, pendulous, bitegmic, crassinucellar. Funicle long. Micropyle ?-stomal. Outer integument ? cell layers thick. Inner integument ? cell layers thick. Parietal tissue? Megasporangium multicellular in chalazal part only. Megagametophyte monosporous, Polygonum-type. Endosperm development cellular. Basal suspensor cell giving way to micropylar endosperm haustorium. Embryogenesis?

Fruit An assemblage of follicles (with persistent and recurved sepals); free part of carpel circumscissilely dehiscing at base and falling off like a lid.

Seeds Aril absent. Seed coat exotestal. Exotestal cells prominent, papillate, tanniniferous, with thickened outer walls. Other testal cell layers absent. Tegmen crushed, consisting of endostomal micropylar operculum (formed from inner integument). Perisperm not developed. Endosperm sparse. Embryo large, straight; suspensor with strongly enlarged not dividing micropylar cell, chlorophyll? Cotyledons two. Germination? First two pairs of seedling leaves opposite.

Phytochemistry Mono- and diglycosides of flavonols (kaempferol, quercetin) present. Myricetin, flavones, non-hydrolyzable tannins, and cyanogenic compounds not found.

Vegetative anatomy Phellogen? Stem cortex with secretory cells and few fibres. Medullary bundles usually absent (present in Peridiscus). Wide primary medullary strands alternating with narrow ones. Vessel elements with scalariform perforation plates; lateral pits scalariform to opposite, bordered pits. Imperforate tracheary xylem elements fibre tracheids and long libriform fibres with bordered pits, usually non-septate. Wood rays uniseriate and homocellular or heterocellular (Soyauxia), or multiseriate heterocellular (Peridiscus, Whittonia). Axial parenchyma apotracheal diffuse. Sieve tube plastids S (Ss?) type. Nodes? Acicular and elongate crystals, crystal sand, styloids, etc. present in parenchyma cells in Soyauxia.

Leaves Alternate (distichous), simple, entire, coriaceous, with ? ptyxis. Stipules single, adaxial, intrapetiolar or pairwise lateral, almost perfoliate, early caducous; leaf sheath absent. Petiole in Peridiscus with pulvinus. Petiole vascular bundle transection annular; petiole with wing bundles (Soyauxia), an adaxial plate (Peridiscus) or adaxial annular bundle (Whittonia). Venation usually pinnate (rarely palmate). Stomata anomocytic or paracytic. Cuticular wax crystalloids as platelets in rosettes. Domatia in vein axils on abaxial side of lamina (Soyauxia?). Idioblasts with crystals. Leaf margin entire.

Inflorescence Axillary, fasciculate, or raceme or spike. Floral prophylls (bracteoles) large, persistent.

Flowers Actinomorphic. Hypogyny to half epigyny. Sepals four to seven, with imbricate? aestivation, caducous, free. Petals five with tubular corona (Soyauxia), free, or absent. Nectariferous disc intrastaminal, cupular or annular, sometimes hairy.

Androecium Stamens c. 30 to more than 100; outer much longer than inner. Filaments free or somewhat connate at base into fascicles (Whittonia), free from tepals. Anthers basifixed or subdorsifixed, non-versatile, disporangiate (Peridiscus, Whittonia) or tetrasporangiate (Soyauxia), introrse, longicidal (dehiscing by longitudinal slits, Peridiscus, Whittonia) or by lateral flaps (Soyauxia). Tapetum secretory. Staminodia absent.

Pollen grains Microsporogenesis simultaneous. Pollen grains tricolpor(oid)ate, shed as monads, ?-cellular at dispersal. Exine semitectate (Soyauxia), with columellate infratectum, reticulate (Soyauxia).

Gynoecium Pistil composed of usually three or four (rarely five) carpels, connate in lower parts. Ovary superior to semi-inferior, unilocular (in Soyauxia with central columella). Stylodia three or four, separate, short. Stigmas punctate, non-papillate, type? Pistillodium absent.

Ovules Placentation usually apical (sometimes free central). Ovules usually six to eight per ovary, orthotropous?, pendulous, bitegmic?, crassinucellar? Micropyle ?-stomal. Outer integument ? cell layers thick. Inner integument ? cell layers thick. Megagametophyte monosporous, Polygonum type? Endosperm development nuclear? Endosperm haustoria? Embryogenesis?

Fruit A single-seeded loculicidal capsule (Soyauxia) or a one-seeded drupe (Peridiscus, Whittonia).

Seeds: Aril absent. Seed coat testal. Testal cells tanniniferous (sometimes dark-staining), thin-walled, more or less collapsed. Tegmen? Perisperm not developed. Endosperm copious, cartilagineous, with thick cell walls (or absent?), probably with hemicellulose. Embryo minute, straight? (curved?), well differentiated, chlorophyll? Cotyledons two, foliaceous. Germination?

Vegetative anatomy Phellogen ab initio superficial. Pericyclic fibres weakly developed. Vessel elements (some of them fibre-like) with scalariform or simple perforation plates; lateral pits? Imperforate tracheary xylem elements tracheids (rare), grading into fibre tracheids and libriform fibres. Wood rays uniseriate or multiseriate, heterocellular? Axial parenchyma apotracheal diffuse, or paratracheal scanty. Xylem diffusely porose, non-storied. Sieve tube plastids Ss type. Nodes 3:3, trilacunar with three leaf traces. Secretory cavities absent. Crystals?

Trichomes Hairs unicellular or multicellular, uniseriate, peltate or clavate; glandular hairs cone-shaped to peltate or spherical, multicellular, resin-secreting.

Leaves Alternate (spiral), simple, entire, membranaceous to coriaceous, sticky and resinous on adaxial side, with ? ptyxis. Stipules cauline, very small, early caducous; leaf sheath absent. Petiole vascular bundle transection arcuate? Venation pinnate. Stomata anomocytic. Cuticular waxes? Domatia as pockets in axils of lateral veins on abaxial side of lamina. Secretory cavities absent. Mesophyll with calciumoxalate, usually as druses (usually in association with vascular strands). Leaf margin serrate; leaf teeth with hydathodes.

Flowers Actinomorphic. Hypanthium present. Epigyny. Sepals five, with valvate aestivation, persistent, free. Petals five, with imbricate aestivation, persistent, free. Nectary absent. Disc absent.

Androecium Stamens five, antesepalous, alternipetalous. Filaments flattened, dentate at apex, winged, free from each other and from tepals. Anthers basifixed to dorsifixed, versatile, tetrasporangiate, introrse, poricidal (dehiscing by basal pores). Tapetum secretory. Staminodia five, intrastaminal, antepetalous, as thin filaments without anthers; each staminodium with one lateral tooth.

Pollen grains Microsporogenesis simultaneous. Pollen grains tricolporoidate or tricolporate, shed as monads, bicellular or tricellular at dispersal. Exine tectate, with columellate? infratectum, perforate or suprarugulate.

Gynoecium Pistil composed of five connate carpels. Ovary inferior, usually quinquelocular (sometimes sexalocular). Styles five, connate in lower part, short. Stigmas five, quinquelobate, arising more or less radially, type? Pistillodium absent.

Ovules Placentation axile. Ovules four to eight per carpel, anatropous, ascending, apotropous, bitegmic, crassinucellar. Micropyle ?-stomal. Outer integument ? cell layers thick. Inner integument ? cell layers thick. Parietal tissue approx. seven cell layers thick. Megagametophyte monosporous, Polygonum type? Endosperm development? Endosperm haustoria? Embryogenesis?

Fruit A lignified septicidal usually single-seeded capsule, with persistent upright sepals and recurved petals.

Seeds: Aril absent? Seed coat testal. Testa more or less cartilaginous. Tegmen? Perisperm not developed. Endosperm sparse or absent? Embryo large, well differentiated, chlorophyll? Cotyledons two. Germination?

Phytochemistry Very insufficiently known. Quercetin-3-O-glycosides and flavone-C-glycosides present. Cyanogenic compounds? Ellagic acid?

Chrysospleniaceae Bercht. et J. Presl, Přir. Rostlin: 259. Jan-Apr 1820 [’Chrysospleniae’]; Pectiantiaceae Raf., Fl. Tellur. 2: 73. Jan-Mar 1837 [’Pectantidia’]; Saxifragopsida Brongn., Enum. Plant. Mus. Paris: xxviii, 107. 12 Aug 1843 [’Saxifragineae’]; Brachycaulaceae Panigrahi et Dikshit in Panigrahi, Proc. 90^th Indian Sci. Congr. Part III (Advance Abstr.): 54. Jan 2003

Distribution Mainly in northern temperate and polar areas; a few species in southern temperate regions, and on tropical mountains (in the Andes).

Habit Usually bisexual (rarely androdioecious), usually perennial herbs (sometimes annual or biennial, rarely somewhat lignified). Some species are succulent and/or xerophytic.

Vegetative anatomy Phellogen ab initio subepidermal or pericyclic. Cortical and medullary vascular bundles present or absent. Young stem with vascular tissue in separate bundles (pseudosiphonostele). Secondary lateral growth usually absent (sometimes present, normal?). Vessel elements usually with simple (rarely scalariform) perforation plates; lateral pits? Imperforate tracheary elements ? with bordered pits, non-septate?, or absent. Wood rays indistinct. Axial parenchyma? Sieve tube plastids Ss type. Nodes usually 3:3, trilacunar with three leaf traces (sometimes 1:1 [Chrysosplenium], 1:2 [Micranthes], unilacunar with one or two traces, or >3:>3 [Astilbe, etc.], multilacunar with several traces; in some species more than 50 vascular bundles proceeding into petiolar base). Secretory cells with proanthocyanidins and/or ellagitannins. Idioblasts with cyanogenic compounds or druses unusual. Calciumoxalate as druses or acicular crystals present in several genera.

Trichomes Hairs unicellular or multicellular, uniseriate or multiseriate; apex often with multicellular gland; chalk glands present in some species?

Leaves Usually alternate (spiral; usually in basal rosette; rarely opposite in inflorescences), simple or pinnately or palmately compound, entire or lobate, with various types of ptyxis. Often with stipules? in inflorescences; leaves sometimes with persistent stipule-like outgrowths (stipules?) at or near base or on petiole (in Astilbe cauline); leaf base often sheathing. Colleters often present. Petiole vascular bundle transection arcuate or annular; petiole sometimes with medullary or adaxial bundles. Venation palmate or pinnate. Stomata usually anomocytic (sometimes anisocytic or diacytic), often present only on adaxial side of lamina. Cuticular wax crystalloids? Hydathodes frequent. Leaf margin usually serrate, often glandular-serrate (rarely entire).

Inflorescence Terminal raceme, spike or head, or raceme-, spike- or head-like, or fasciculate or panicle (flowers rarely solitary).

Flowers Usually actinomorphic (rarely obliquely zygomorphic). Hypanthium usually present. Epigyny or half epigyny (sometimes pseudohypogyny; variation also between different morphs of heterostylous species). Sepals (three to) five (to ten), with imbricate or valvate aestivation, median sepal adaxial, free. Petals (four or) five (to ten), with imbricate or valvate aestivation, free (sometimes absent). Nectariferous disc intrastaminal (sometimes absent).

Androecium Stamens (three to) five, alternisepalous (sometimes obhaplostemonous), or (4–)5+(4–)5, obdiplostemonous (rarely up to 15). Filaments free from each other and from tepals. Anthers usually basifixed (rarely somewhat dorsifixed), usually non-versatile, usually tetrasporangiate (in Leptarrhena and Tanakaea disporangiate), introrse or latrorse (in Tolmiea median anthers extrorse and lateral anthers introrse), usually longicidal (dehiscing by longitudinal slits; in Leptarrhena and Tanakaea apically). Tapetum secretory. Staminodia absent?

Pollen grains Microsporogenesis simultaneous. Pollen grains 2–3-colporoidate, 2–3-colpate, 2–3-colporate or 6–9-porate, shed as monads, bicellular at dispersal. Exine tectate or semitectate, with columellate infratectum, perforate, reticulate, or striate, echinulate or spinulate.

Gynoecium Pistil composed of two (to five) usually connate carpels (connate at least at base; in Darmera and certain species of Astilbe free) with various orientation, numerous species with median carpels (some species with oblique carpels), sometimes more or less open ventrally in free distal part. Ovary inferior or semi-inferior, unilocular (apocarpy) or bilocular (rarely trilocular). Stylodia usually two (rarely three), free. Stigmas usually capitate (rarely decurrent), papillate, Dry or Wet type. Pistillodium absent.

Ovules Placentation axile to parietal. Ovules nine to more than 30 per carpel, anatropous, pendulous or ascending, usually bitegmic (in Darmera and Micranthes unitegmic), crassinucellar. Micropyle bistomal, often Z-shaped (zig-zag). Outer integument two cell layers thick. Inner integument two cell layers thick (integument in Darmera four to six cell layers thick). Parietal tissue three to five cell layers thick. Nucellar cap present. Megagametophyte usually monosporous, Polygonum type (rarely disporous, Allium type). Synergids usually with a filiform apparatus. Endosperm development ab initio cellular, helobial or nuclear. Endosperm haustoria of various types present in some species. Embryogenesis solanad.

Seeds Aril absent? Seed coat exotestal (and sometimes endotegmic), usually with various sculpturing (in Leptarrhena and Sullivantia with wings). Exotestal cells often with outer wall (sometimes radial walls) thickened. Inner pigmented layer often present. Tegmen usually crushed. Endotegmen in Heuchera and Tolmiea thick-walled, crystalliferous. Perisperm not developed. Endosperm usually copious, oily. Embryo usually small (sometimes large), straight, without chlorophyll. Cotyledons two. Germination phanerocotylar.

Cytology x = 7 (most Saxifragaceae), x = 9–14 (many species of Saxifraga), x = 11 (Chrysosplenium, Peltoboykinia), x = 12 (Chrysosplenium), x = 15 (Rodgersia), x = 17 (Astilboides, Bergenia, Darmera, Mukdenia), x = 18 (Rodgersia) – Polyploidy (also autopolyploidy) and aneuploidy often occurring; in Saxifraga the diploid chromosome number varies widely (2n = 12 to c. 220).

DNA Intron absent from plastid gene rpl2. Different combinations of plastid and nuclear genomes present (plastid genome in Tellima also present in Mitella).

Phytochemistry Flavonols (kaempferol, quercetin, myricetin), afzelechin (a flavan-3-ol), cyanidin, oleanolic acid derivatives, bergeniin (C-glycoside of gallic acid), proanthocyanidins (prodelphinidins), hydrolyzable ellagic acid or gallic acid based tannins (tellimagrandin I, tellimagrandin II), condensed tannins (from procyanidin or prodelphinidin), cyanogenic compounds, germacrane-like compounds, and arbutin present. Cyanogenesis via isoleucine or valine. Iridoids not found. Aluminium accumulated in some species.

Systematics Saxifraga (c 390; Europe, arctic and temperate Asia, North Africa, temperate and alpine North America, temperate and alpine South America); Astilbe (18–23; the Himalayas, China, Japan, Southeast Asia, Malesia to New Guinea, southeastern Canada, eastern United States), Leptarrhena (1; L. pyrolifolia; western Canada, northwestern United States incl. Alaska), Tanakaea (1; T. radicans; China, Japan), Saniculiphyllum (1; S. guangxiense; northwestern Guangxi, southeastern Yunnan), Jepsonia (3; J. heterandra, J. malvifolia, J. parryi; southern California, northwestern Mexico), Telesonix (2; T. heucheriformis, T. jamesii; Rocky Mountains in the United States), Sullivantia (3; S. oregana, S. renifolia, S. sullivantii; the United States), Bolandra (2; B. californica, B. oregana; western United States), Suksdorfia (1; S. violacea; southwestern Canada, western United States), Boykinia (8 incl. ‘Suksdorfia’ ranunculifolia; Japan, western Canada, western United States incl. Alaska, northwestern Mexico), Hieronymusia (1; H. alchemilloides; Bolivia, Argentina)?; Mitella (2; M. diphylla, M. nuda; southern Canada, United States), Bensoniella (1; B. oregona; western United States), Tolmiea (2; T. diplomenziesii, T. menziesii; western Canada, western United States incl. Alaska), Lithophragma (9; western United States), ‘Heuchera’ (55–60; Canada, United States incl. southern Alaska, Mexico; polyphyletic), Pectiantia (c 13; P. breweri, P. ovalis, ‘Mitella’ furusei, P. pentandra; ‘Mitella’ kiusiana, M. yoshinagae; M. acerina, M. amamiana, M. doiana, M. formosana, M. japonica, M. koshiensis, M. pauciflora, M. stylosa; Japan, the Ryukyu Islands, Taiwan, western Canada, western United States incl. Alaska), Tellima (10; western Canada, western United States incl. southern Alaska), Tiarella (3; T. cordifolia, T. polyphylla, T. trifoliata; eastern Himalayas, China, Japan, western and southeastern Canada, western and eastern United States), ‘Mitella’ integripetala (Japan), Elmera (1; E. racemosa; southwestern British Columbia, Washington, Oregon), Mitellastra (1; M. caulescens; southwestern Canada, western United States), Ozomelis (4; O. diversifolia, O. stauropetala, O. trifida, Conimitella williamsii; southwestern Canada, western United States incl. southern Alaska), Cascadia (1; C. nuttallii; Oregon, Washington), Saxifragodes (1; S. albowiana; 51°S in Chile to Tierra del Fuego); Darmera (1; D. peltata; southwestern Oregon, northern California), Astilboides (1; A. tabularis; northern China), Rodgersia (5; R. aesculifolia, R. henrici, R. pinnata, R. podophylla, R. sambucifolia; Nepal, the Himalayas, China, the Korean Peninsula, Japan), Bergenia (10; temperate and subtropical regions of western China to Japan), Mukdenia (2; M. acanthifolia, M. rossii; northern China, Manchuria, the Korean Peninsula), Oresitrophe (1; O. rupifraga; northeastern China); Peltoboykinia (1; P. tellimoides; Japan), Chrysosplenium (70–75; Europe, temperate and arctic Asia, North America, southern South America); Micranthes (c 45; Europe, arctic and temperate Asia, arctic and mountain regions in North America, alpine and mountain regions in Mexico and South America).

Saxifragaceae are sister-group to Ribes (Grossulariaceae).

According to the study by Soltis, Morgan, Grable & al. (1993), Astilbe (Astilbeae Small, Man. S.E. Fl.: 590. 30 Nov 1933), Chrysosplenium (Chrysosplenieae Dumort., Fl. Belg.: 84. 1827) and Peltoboykinia form three basal clades, Astilbe being sister to Saxifragoideae Beilschm. in Flora 16(Beibl. 7): 94. 14 Jun 1833 [‘Saxifrageae’] which comprise all other Saxifragaceae. On the other hand, Deng & al. (2015) reveals Saxifraga as sister to the remaining Saxifragaceae. Two main clades may be identified: the saxifragoids (Saxifrageae Dumort., Fl. Belg.: 84. 1827), the astilboids and the heucheroids (Heuchereae Bartl., Ord. Nat. Plant.: 312. Sep 1830 [‘Heucherea’]).

Cladogram of Saxifragaceae based on DNA restriction site analysis data (Soltis, Morgan, Grable & al. 1993).

Cladogram of Saxifragaceae based on Deng & al. (2015)

Vegetative anatomy Phellogen? Stem without endodermis. Vessel elements with scalariform perforation plates; lateral pits scalariform to opposite. Imperforate tracheary xylem elements very short thick-walled tracheids. Wood rays uniseriate and homocellular, or uniseriate or biseriate and heterocellular. Axial parenchyma apotracheal diffuse or diffuse-in-aggregates, or paratracheal scanty. Sieve tube plastids Ss type. Nodes 1:1, unilacunar with one leaf trace. Crystals?

Leaves Alternate (spiral), simple, entire, coriaceous, with ? ptyxis. Stipules and leaf sheath absent. Petiole vascular bundle transection arcuate? Venation pinnate. Stomata anomocytic. Cuticular wax crystalloids? Cuticle thick. Leaf margin biserrate; leaf teeth eglandular, possibly with hydathodes (water pores absent).

Flowers Actinomorphic, small. Hypanthium present? Hypogyny. Sepals four (or five), with imbricate aestivation, persistent, connate at base. Petals four (or five), with imbricate aestivation, stipitate, caducous, free. Nectary absent. Disc absent.

Androecium Stamens four or eight, in one whorl (or two whorls?), antepetalous and alternipetalous. Filaments filiform, connate at base, free from tepals. Anthers basifixed, non-versatile, tetrasporangiate, latrorse, longicidal (dehiscing by longitudinal slits). Tapetum secretory. Staminodia absent.

Pollen grains Microsporogenesis simultaneous. Pollen grains tricolporate, shed as monads, ?-cellular at dispersal. Exine semitectate,with columellate? infratectum, reticulate to rugulate.

Gynoecium Pistil composed of four (or five), stipitate, antepetalous carpels, connate only at base. Ovary superior, unilocular (apocarpy) or usually quadrilocular (sometimes quinquelocular in proximal part?). Stylodia very short. Stigmas small, type? Pistillodium absent.

Ovules Placentation (sub)marginal (ventral, with branched placentae). Ovules c. 15 to more than 100 per carpel, anatropous, bitegmic, crassinucellar. Micropyle exostomal. Outer integument ? cell layers thick. Inner integument ? cell layers thick. Parietal tissue approx. four cell layers thick. Megagametophyte monosporous, Polygonum type. Endosperm development ab initio cellular. Endosperm haustoria? Embryogenesis?

Seeds Aril absent. Seed very small. Seed coat exotestal. Testa thin, with ridges and one or two narrow longitudinal wings, extended at both ends. Exotestal cells longitudinally elongate, with thickened outer walls, without mechanical layers. Inner testal cell layers often crushed. Tegmen? Perisperm not developed. Endosperm copious, fleshy. Embryo very small, chlorophyll? Cotyledons two? Germination?

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SUPERROSIDAE W. S. Judd, D. E. Soltis et P. S. Soltis

SAXIFRAGALES Bercht. et J. Presl

ALTINGIACEAE Horan.

APHANOPETALACEAE Doweld

CERCIDIPHYLLACEAE Engl.

CRASSULACEAE J. St.-Hil.

CYNOMORIACEAE Endl. ex Lindl.

DAPHNIPHYLLACEAE Müll.-Arg.

GROSSULARIACEAE DC.

HALORAGACEAE R. Br.

HAMAMELIDACEAE R. Br.

ITEACEAE J. Agardh

MEDUSANDRACEAE Brenan

PAEONIACEAE Raf.

PENTHORACEAE Rydb. ex Britton

PERIDISCACEAE Kuhlm.

PTEROSTEMONACEAE Small

SAXIFRAGACEAE Juss.

TETRACARPAEACEAE Nakai