[Gunnerales+Pentapetalae]
Gunnerineae Shipunov in A. Shipunov et J. L. Reveal in Phytotaxa 16: 63. 4 Feb 2011
Habit Usually monoecious or bisexual (sometimes polygamomonoecious or dioecious), usually perennial (rarely annual) herbs.
Vegetative anatomy Phellogen? Pith with sclerenchymatous diaphragms. Stem usually with polystele consisting of few to several hundred vascular bundles, each one with endodermis; stolon with siphonostele. Secondary lateral growth usually absent. Vessel elements with scalariform, simple or reticulate-scalariform perforation plates; lateral pits alternate or opposite, bordered pits. Imperforate tracheary xylem elements tracheids or fibre-tracheids? with simple or bordered pits, non-septate. Wood rays uniseriate, homocellular, or absent. Axial parenchyma absent or very rare. Sieve tube plastids S, Pcs (P1b) type, with protein crystals and usually with starch grains. Nodes ≥3:≥3, trilacunar or multilacunar with three or more leaf traces. Secretory cavities absent. Epidermal cells sometimes resin-producing. Calciumoxalate druses often frequent.
Trichomes Hairs unicellular or multicellular, uniseriate or multiseriate, stalked and globular hairs as well as spines often present (hairs sometimes absent).
Leaves Alternate (spiral) or opposite, simple, entire or palmately lobed, sometimes peltate, with plicate ptyxis. Stipule large, scale-like, axillary, intrapetiolar (squamula intravaginalis) or stipules two, simple, lateral; leaf sheath absent. Petiole vascular bundle transection complex. Venation pinnate or subpalmate, actinodromous or palinactinodromous (sometimes palmate-flabellate). Stomata anomocytic. Cuticular wax crystalloids at least sometimes as rodlets. Lamina without secretory cavities. Epidermis sometimes with balsam-producing resinous cells and subepidermal abaxial cells sometimes tanniniferous. Mesophyll sometimes with calciumoxalate druses. Leaf margin dentate, serrate or crenate; leaf teeth often hydathodal, usually with glandular tip and two veins.
Inflorescence Axillary or pseudoterminal, simple or branched spike, capitulum, spadix or panicle, or terminal and spike- or catkin-like on lateral shoots.
Flowers Actinomorphic, small. Epigyny. Tepals 2(–3)+2(–3), with valvate aestivation, sepaloid, transversal, free (sometimes absent). Nectary absent. Disc absent.
Androecium Stamens one to eight, alternisepalous (alternitepalous). Filaments free from each other, free from or somewhat adnate to tepals. Anthers basifixed, non-versatile, tetrasporangiate, introrse or latrorse, longicidal (dehiscing by longitudinal slits). Tapetum secretory. Staminodia absent.
Pollen grains Microsporogenesis simultaneous. Pollen grains usually tricolpate (sometimes tetra- or pentacolpate), usually shed as monads (sometimes as tetrads), bicellular at dispersal. Exine usually semitectate (sometimes intectate), with columellate infratectum, reticulate or microreticulate.
Gynoecium Pistil composed of two (to four) connate carpels. Ovary superior, unilocular (due to pseudomonomery; sometimes partially tri- or quadrilocular). Style single, simple, or absent (stylodia sometimes three or four). Stigma bilobate, papillate, Dry type (or almost so). Pistillodium absent.
Ovules Placentation usually apical or subapical (sometimes central-axile). Ovule usually one per ovary (ovules sometimes two to more than 50 per carpel), anatropous, pendulous or horizontal, bitegmic, crassinucellar. Micropyle usually endostomal (sometimes bistomal). Megagametophyte usually tetrasporous, 16-nucleate, Peperomia type, with six antipodal cells and a group of cells fusing into secondary megagametophyte nucleus (sometimes disporous, 8-nucleate, Allium type). Endosperm development usually ab initio cellular (sometimes nuclear). Endosperm haustoria? Embryogenesis?
Fruit Usually a drupe (sometimes a schizocarp with capsular mericarps, rarely a nutlet).
Seeds Aril absent. Seed coat testal? Exotestal cells sometimes with thickened outer walls. Endotesta? Tegmen? Perisperm not developed. Endosperm copious, oily, starchy and with aleurone, usually with crystalloids. Embryo small, usually well differentiated, chlorophyll? Cotyledons two. Germination phanerocotylar.
Cytology n = 10, 12, 17, 27
DNA d copy of nuclear gene RPB2 lost. Mitochondrial gene rps11 probably lost. Nuclear gene euAP3?
Phytochemistry Flavonols (kaempferol, quercetin, myricetin), hyperoside (quercetin 3-O-galactoside), isoquercetin (quercetin 3-O-glucoside), cyanidin pelargonidin, caffeic acid, ellagic and gallic acids, ellagitannins, polyphenols (e.g. galloyl quininic acid and galloyl esters of quininic acid), saponins, dihydrochalcones, p-coumaric acid, sinapic acid, p-hydrobenzoic acid, vanillic acid, and syringinic acid present. Ethereal oils in the form of carvone, perillinic acid, 1,8-cineol, diosphenol, trans-pinocarvenol, pinocarvone, trans-pinocarvone, α-pinene, β-selinene, etc. Cyanogenesis via phenylalanine, isoleucine or valine.
Systematics There is almost 100% bootstrap support for Gunnerales being sister-group to Pentapetalae.
GUNNERACEAE Meisn. |
Genera/species 1/66
Distribution Eastern and southern Africa, Madagascar, Malesia, New Guinea, the Solomon Islands, Tasmania, New Zealand, Hawaii, Central America, South America (above all in the Andes), Juan Fernandez, the Falkland Islands.
Fossils Fossil pollen grains similar to those in Gunnera are known from the Turonian of Peru. Campanian to Early Cenozoic pollen fossils of possible gunneraceous origin have been found in the Southern Hemisphere, including present-day Australia and Antarctica, and in West Africa and North America (possibly also Asia). Similar pollen fossils are known also from present-day India and the Indian Ocean from the Palaeogene onwards.
Habit Usually monoecious or bisexual (sometimes polygamomonoecious; rarely dioecious), usually perennial herbs (Gunnera herteri is an annual). Buds often covered by large bracts. Apex of stolon with pairwise or simple ocreoid (ochrea-like) bracts. Often with numerous simple or divided scales between leaves.
Vegetative anatomy Wartlike mucilaginous adventitious root primordia present between stem leaves (primordia normally not developing into adventitious roots), into which Nostoc (and/or Chlorococcus?) cells penetrate via hydathodes or mucilage glands, forming intercellular colonies in tissues inside. Roots triarch to polyarch. Phellogen? Medulla septate through sclerenchymatous diaphragms? Stem (including rhizome) with polystele consisting of few to several hundred vascular bundles, each with endodermis; stolon with vascular cylinder as siphonostele. Secondary lateral growth absent. Vessel elements with scalariform (bars few to more than 150) or simple (in stem of species with large leaves) perforation plates; lateral pits? Imperforate tracheary xylem elements ? (tracheids absent), thick-walled, with simple pits. Wood rays absent. Axial parenchyma? Sieve tube plastids Pcs type (P1b type), with protein crystals and starch grains. Nodes multilacunar with ? leaf traces. Secretory cavities absent. Calciumoxalate druses often frequent. Tannins abundant.
Trichomes Hairs unicellular, simple, uniseriate (hairs absent in Gunnera herteri), in subgenus Panke also multiseriate, stalked and globular hairs.
Leaves Alternate (spiral; concentrated to shoot apices; gland-tipped stolon cataphylls [prophylls?] often opposite), simple, entire or palmately lobed, sometimes peltate, often very large (diameter of lamina sometimes more than three metres), with conduplicate-plicate? ptyxis. Stipule? large, scale-like, axillary, intrapetiolar (squamula intravaginalis); ochrea (membranous scale surrounding shoot apex) present in Gunnera lobata and G. magellanica; leaf sheath absent. Small glandular colleters present in leaf axils of Gunnera herteri. Petiolar anatomy and petiole vascular bundle transection complex. Venation pinnate or subpalmate, palinactinodromous or actinodromous. Stomata anomocytic. Cuticular waxes? Lamina without secretory cavities. Leaf margin dentate, serrate or crenate, with distinct hydathodes; leaf teeth with distally expanded glandular tip and two veins. Spines present on petiole and abaxial side of lamina.
Inflorescence Axillary or pseudoterminal, simple or branched spike, capitulum, spadix or panicle. Lower flowers usually female, upper flowers male. Floral prophylls (bracteoles) absent?
Flowers Actinomorphic, small. Epigyny. Tepals 2(–3)+2(–3) (inner tepals, petals, often absent, especially in female flowers), with apert aestivation, sepaloid, transverse, free. Nectary absent. Disc absent.
Androecium Stamens (one or) two (or three), transverse, antepetalous, alternisepalous. Filaments short, free from each other, free from or somewhat adnate to tepals. Anthers basifixed, non-versatile, tetrasporangiate, introrse or latrorse?, longicidal (dehiscing by longitudinal slits). Tapetum secretory. Female flowers often with staminodia.
Pollen grains Microsporogenesis simultaneous. Pollen grains usually tricolpate (sometimes tetra- or pentacolpate), fossaperturate with bulging mesocolpia, shed as monads, bicellular at dispersal. Exine semitectate, with columellate? infratectum, reticulate to microreticulate.
Gynoecium Pistil composed of two connate carpels, transverse, alternitepalous; compitum present. Ovary inferior, unilocular due to pseudomonomery (sometimes bilocular). Style single, simple, short, or absent. Stigma bilobate, hairy, papillate, Dry type. Male flowers often with pistillodium.
Ovules Placentation apical or subapical. Ovule one (or two) per ovary, anatropous, pendulous, epitropous, bitegmic, crassinucellar. Micropyle endostomal. Outer integument approx. three cell layers thick. Inner integument (two? to) four cell layers thick. Megagametophyte tetrasporous, 16-nuclear, Peperomia type, with six antipodal cells and additional cells fusing forming secondary megagametophyte nucleus. Endosperm development cellular. Endosperm haustoria? Embryogenesis?
Fruit Usually a drupe (rarely a nutlet).
Seeds Aril absent. Seed coat? Exotesta? Endotesta? Tegmen? Perisperm not developed. Endosperm copious, oily, starchy and with aleurone, with crystalloids. Suspensor without haustorium. Embryo minute, eccentric, well differentiated, chlorophyll? Cotyledons two. Germination phanerocotylar.
Cytology n = 12, 17, 27
DNA AP3-duplication [euAP3- + TM6-paralogues]; PI-dB motif present? Mitochondrial genes rps2 and rps11 probably absent (lost). Nuclear gene euAP3?
Phytochemistry Flavonols (kaempferol, quercetin), hyperoside (quercetin 3-O-galactoside), isoquercetin (quercetin 3-O-glucoside), pelargonidin, caffeic acid, ellagic acid, ellagitannins, and saponins present. Cyanogenesis via phenylalanine, isoleucine or valine. Proanthocyanidins not found.
Use Ornamental plants, medicinal plants; Gunnera chiloensis used for dyeing and tanning and the petioles as vegetables (nalca, rahuay) by many South American indian tribes.
Systematics Gunnera (c 40; tropical East and southern Africa, Madagascar, Malesia, New Guinea, the Solomon Islands, Tasmania, New Zealand, the Hawaiian Islands, Central and South America (above all in the Andes), Juan Fernandez, the Falkland Islands).
Gunnera is sister to Myrothamnus (Myrothamnaceae).
Gunnera herteri seems to be sister to the remaining species of Gunnera.
MYROTHAMNACEAE Nied. |
Myrothamnales Nakai ex Reveal in Phytologia 74: 176. 25 Mar 1993; Myrothamnanae Takht., Divers. Classif. Fl. Pl.: 134. 24 Apr 1997
Genera/species 1/2
Distribution East Africa, northwestern and northeastern South Africa, Madagascar.
Fossils Tetrahedral tetrads of triporoidate to tricolporoidate pollen grains (e.g. Virgo amiantopollis), resembling those in Myrothamnus, have been found in the mid-Albian to the Cenomanian of eastern North America and Portugal.
Habit Dioecious, deciduous shrubs. Strongly poikilohydric aromatic xerophytes (‘resurrection plants’). Lateral branches usually as short shoots. Stems and branches narrowly winged.
Vegetative anatomy Phellogen? Medulla septate by sclerenchymatous diaphragms. Primary medullary strands narrow, uniseriate. Vessel elements with scalariform or reticulate-scalariform perforation plates; lateral pits alternate or opposite, bordered pits. Imperforate tracheary xylem elements tracheids with bordered pits, non-septate. Wood rays uniseriate, homocellular. Axial parenchyma absent or very scarce (apotracheal?). Sieve tube plastids S type. Nodes 3:3, trilacunar with three leaf traces, split lateral, of ‘common gap type’. Epidermis with resin-producing enlarged cells. Inner walls of xylem elements with lipids. Calciumoxalate present as druses. Xylem with lipids.
Trichomes Hairs absent.
Leaves Opposite, simple, entire, with plicate ptyxis. Stipules two, simple, lateral, small, persistent on base of leaf sheath; petiole base sheathing, fused and persistent. Petiole vascular bundle transection arcuate. Leaf sheath with four bundles: two bundles running directly to mid-vein, and two bundles forming commissural veins. Lamina as dry strongly folded and blackening, otherwise fan-shaped and outspread (five to seven times folded). Venation palmate-flabellate (open, dichotomously branched). Cells with lipids in connection with vascular strands. Stomata anomocytic. Cuticular wax crystalloids as tiny rodlets. Epidermis with balsam producing resinous cells. Subepidermal abaxial cells with tannins. Mesophyll with calciumoxalate druses. Leaf margin serrate or dentate towards apex.
Inflorescence Terminal, spike- or catkin-like, on lateral shoots. Male inflorescence in Myrothamnus moschata with terminal flower.
Flowers Actinomorphic or slightly zygomorphic (female flowers), very small. Epigyny? Tepals absent in female flowers and probably in male flowers; male flowers with one to more than four sepaloid scale-like free leaves (bracts or tepals?), or scale leaves absent; terminal flowers with four sepaloid scale-like free leaves as well as bracts and floral prophylls (bracteoles). Nectary absent. Disc absent.
Androecium Stamens three or four, or three to eight, respectively, alternitepalous. Filaments free (when stamens three or four) or connate at base (when stamens three to eight). Anthers basifixed, non-versatile, tetrasporangiate, latrorse, longicidal (dehiscing by longitudinal slits), with a proximal (basal) bifid orifice; connective prolonged. Tapetum secretory, with binucleate cells. Staminodia absent.
Pollen grains Microsporogenesis simultaneous. Pollen grains indistinctly shortly tricolpate to almost triporate, shed as tetrads, bicellular at dispersal. Pores possibly arranged according to Garside’s rule. Exine intectate, columellate, with papillate clavate columellae.
Gynoecium Pistil composed of three or four basally connate carpels; odd carpel abaxial; carpels with epidermal oil cells; terminal flowers with four alternitepalous carpels; compitum absent. Ovary tri- or quadrilocular at base. Stylodia three or four, short, recurved. Stigma wing-shaped, spatulate, adaxially decurrent, papillate, Dry type or almost so? Pistillodium absent.
Ovules Placentation central-axile (submarginal). Ovules approx. ten to more than 50 per carpel, anatropous, horizontal, bitegmic, crassinucellar. Micropyle bistomal. Outer integument ? cell layers thick. Inner integument ? cell layers thick. Megagametophyte disporous, 8-nucleate, Allium type. Endosperm development ab initio nuclear. Endosperm haustoria? Embryogenesis?
Fruit A schizocarp with (follicular or) ventricidal-septicidal capsular mericarps.
Seeds Aril absent. Seed coat exotestal. Exotestal cells with somewhat thickened outer walls. Endotesta? Tegmen? Perisperm not developed. Endosperm copious, oily. Embryo small, poorly (or well?) differentiated, chlorophyll? Cotyledons two. Germination?
Cytology n = 10 – Chloroplasts with a unique type of grana.
DNA Mitochondrial genes rps2 and rps11 probably absent (lost). Nuclear gene euAP3?
Phytochemistry Flavonols (kaempferol, quercetin, myricetin), cyanidin, ellagic and gallic acid, ellagitannins, gallotannins, galloyl quininic acid, galloyl esters of quininic acid, chalcones, dihydrochalcones, p-coumaric acid, sinapic acid, p-hydrobenzoic acid, vanillic acid, and syringinic acid present. Ethereal oils in the form of carvone, perillinic acid, 1,8-cineol, diosphenol, trans-pinocarvenol, pinocarvone, trans-pinocarvone, α-pinene, β-selinene, etc. Cyanogenesis via phenylalanine, isoleucine or valine. Foliar mesophyll cell walls containing arabinans and arabinogalactan proteins in a pectic matrix.
Use Medicinal plants.
Systematics Myrothamnus (2; M. flabellifolia: tropical East Africa, northwestern and northeastern South Africa; M. moschata: Madagascar).
Myrothamnus is sister to Gunnera (Gunneraceae).
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