APIIDAE M. J. Donoghue et P. D. Cantino

Donoghue et Cantino in Taxon 56: E31. Aug 2007


[Escalloniaceae+[Bruniales+Dipsapiidae]]


ESCALLONIACEAE R. Br. ex Dumort.

Dumortier, Anal. Fam. Plant.: 35, 37. 1829, nom. cons.

Escalloniales R. Brown in C. F. P. von Martius, Consp. Regn. Veg.: 47. Sep-Oct 1835 [’Escallonieae’]; Polyosmaceae Blume, Mus. Bot. 1: 258. 1851; Eremosynaceae Dandy in J. Hutchinson, Fam. Fl. Pl., ed. 2: 460. 4 Jun 1959; Tribelaceae (Engl.) Airy Shaw in Kew Bull. 18: 269. 8 Dec 1965; Anopteraceae Doweld, Tent. Syst. Plant. Vasc.: li. 23 Dec 2001; Escallonianae Doweld, Tent. Syst. Plant. Vasc.: li. 23 Dec 2001; Tribelales Doweld, Tent. Syst. Plant. Vasc.: li. 23 Dec 2001; Escalloniineae Shipunov in A. Shipunov et J. L. Reveal in Phytotaxa 16: 63. 4 Feb 2011

Genera/species 7/c 125

Distribution South America, with their largest diversity in the Andes, the Mascarene Islands, southwestern West Australia, southeastern Australia, Tasmania, southern Chile to Tierra del Fuego, eastern Himalaya and southern China to Southeast Asia, Malesia, New Guinea, tropical Australia, New Caledonia.

Fossils Fossil leaves, flowers and fruits of Escallonia have been reported at least from Eocene layers in Chile.

Habit Usually bisexual (rarely unisexual), usually evergreen trees and shrubs (Valdivia gayana is a small shrub; Tribeles australis is a low procumbent and creeping shrub; Eremosyne pectinata is an annual herb).

Vegetative anatomy Phellogen usually superficial (in Escallonia ab initio deeply seated). Narrow primary medullary rays alternating with wide rays. Endodermis absent. Vascular cylinder complete in Forgesia. Vessel elements usually with scalariform (in Eremosyne and some species of Escallonia simple) perforation plates (in Polyosma scalariform with very numerous transverse ribs); lateral pits alternate, scalariform or opposite, bordered pits. Imperforate tracheary xylem elements tracheids (at least in Forgesia and Polyosma also fibre tracheids) with bordered pits, non-septate (also vasicentric tracheids). Wood rays uniseriate or multiseriate, homocellular or heterocellular (sometimes storied). Axial parenchyma usually apotracheal diffuse or diffuse-in-aggregates (at least in Forgesia and Polyosma also paratracheal scanty). Sieve tube plastids S type. Nodes in Eremosyne, Escallonia, Polyosma, and Tribeles 1:1, unilacunar with one leaf trace, in Anopterus, Forgesia and Valdivia 3:3, trilacunar with three traces. Pericycle in Polyosma with sclereids; pericyclic envelope in Forgesia with sclereids. Secretory cavities absent. Heartwood in some species with gum-like substances. Styloids and/or elongate calciumoxalate crystals present in some species of Escallonia. Druses present in Polyosma and in cortex of Forgesia.

Trichomes Hairs usually unicellular (in Anopterus and Valdivia also multicellular, simple, uniseriate; in Polyosma crescent-shaped with base perforated and sunken into epidermis), thick-walled (sometimes furcate); glandular hairs with uniseriate stalk and globular head (sometimes peltate-lepidote; glandular hairs in Escallonia also multiseriate with multicellular head); cells in heads of glandular hairs with vertically radiating walls.

Leaves Usually alternate (spiral; in Polyosma opposite), simple, usually entire (in Eremosyne usually pinnately to palmately lobed), often coriaceous, usually with supervolute (sometimes conduplicate) ptyxis. Stipules usually absent (Escallonia sometimes with prickly stipules); leaf sheath absent. Petiole vascular bundle transection arcuate. Venation usually pinnate (in Eremosyne palmate, acrodromous), usually semicraspedodromous (in Polyosma often brochidodromous). Stomata paracytic. Cuticular wax crystalloids? Druses present in Polyosma. Leaf margin entire, crenate, serrate or biserrate, often with wide glandular teeth and two accessory veins; apical cells of glandular hairs radially arranged.

Inflorescence Terminal or axillary, usually racemes (in Eremosyne terminal cyme consisting of dichasia; flowers in Tribeles solitary terminal). Floral prophylls (bracteoles) absent in Eremosyne.

Flowers Actinomorphic. Usually epigyny (sometimes hypogyny; in Eremosyne and Tribeles partial epigyny). Sepals usually five (in Anopterus six to nine; in Valdivia five to seven; in Polyosma four), with valvate or imbricate aestivation (in Eremosyne minute, with valvate aestivation; in Tribeles with imbricate aestivation), usually more or less connate and persistent. Petals usually five (in Valdivia five to seven; in Anopterus six to nine; in Polyosma four), usually with imbricate aestivation (in Forgesia and Valdivia valvate; in Tribeles shortly clawed, with contorted aestivation; in Polyosma four, with valvate aestivation), free, deciduous. Nectariferous disc intrastaminal (absent in Eremosyne and Tribeles).

Androecium Stamens usually five (in Valdivia five to seven; in Anopterus six to nine; in Polyosma four), haplostemonous, antesepalous, alternipetalous. Filaments in Eremosyne and Tribeles subulate, free from each other and from petals. Anthers usually dorsifixed (rarely basifixed), often versatile, disporangiate, usually introrse (in Eremosyne introrse to latrorse, versatile; in Tribeles extrorse), longicidal (dehiscing by longitudinal slits). Tapetum secretory, with binucleate cells (Escallonia). Placentoid present. Staminodia absent.

Pollen grains Microsporogenesis simultaneous. Pollen grains usually tricolporate (in Polyosma triporate; in Anopterus sometimes tetracolporate), shed as monads, bicellular at dispersal. Exine tectate or semitectate, with columellate infratectum, usually perforate to reticulate or finely reticulate.

Gynoecium Pistil composed of usually two (sometimes four; in Tribeles three) connate carpels; transverse or median carpel adaxial (ovary median in Escallonia). Ovary usually inferior (sometimes semi-inferior or superior), usually partially bilocular with incomplete septa in lower part (in Eremosyne bilocular; in Tribeles trilocular; in Polyosma usually unilocular). Style usually single and simple, sometimes bifid or trifid (stylodia in Eremosyne two, free or connate at base; in Anopterus and Forgesia more or less free), often long. Stigma capitate, punctate or clavate to bilobate to quinquelobate, non-papillate, Wet type. Pistillodium absent.

Ovules Placentation usually parietal (sometimes more or less basal; in Polyosma strongly intrusively parietal; in Eremosyne and Tribeles axial). Ovules usually numerous (in Eremosyne one, basal, ascending) per carpel, anatropous, usually unitegmic (in Tribeles bitegmic), usually tenuinucellar (in Polyosma often almost crassinucellar). Micropyle in Tribeles ?-stomal. Integument five to ten (in Polyosma up to ten) cell layers thick. Outer integument in Tribeles ? cell layers thick. Inner integument in Tribeles ? cell layers thick. Parietal tissue approx. one cell layer thick (Polyosma). Megagametophyte monosporous, Polygonum type. Endosperm development nuclear (or cellular?). Endosperm haustorium micropylar. Embryogenesis?

Fruit Usually a septicidal (in Eremosyne and Tribeles loculicidal) capsule, often dehiscing laterally (fruit in Valdivia dry, indehiscent; in Polyosma a one-seeded drupe).

Seeds Aril present in Eremosyne. Testa in Anopterus winged. Exotestal cells usually with inner walls thickened (in, e.g., Anopterus) and lignified, often elongate (in, e.g., Anopterus; in Tribeles palisade). Perisperm not developed. Endosperm copious, fleshy, usually oily (in Polyosma thick-walled, starchy). Embryo usually small, straight, usually well differentiated (in Polyosma undifferentiated), chlorophyll? Cotyledons two. Germination?

Cytology n = 12 (Escallonia)

DNA Mitochondrial intron coxII.i3 lost (Escallonia). I copy of nuclear gene RPB2 present (Escallonia).

Phytochemistry Flavonols (kaempferol, quercetin), cyanidin, delphinidin, Route I secoiridoids (e.g. daphylloside), Route II decarboxylated iridoids, diterpene alkaloids (anopterine etc. in Anopterus), and saponins present. Ellagic acid and cyanogenic compounds not found. Aluminium accumulated in Polyosma.

Use Ornamental plants (Escallonia), timber (Polyosma), dyeing substances.

Systematics Eremosyne (1; E. pectinata; southwesternmost Western Australia), Anopterus (2; A. glandulosus: western and southern Tasmania; A. macleayanus: southeasternmost Queensland, northeastern New South Wales), Polyosma (c 60; eastern Himalayas and southern China and eastwards to eastern Queensland, eastern New South Wales and New Caledonia), Tribeles (1; T. australis; temperate Chile and Argentina), Escallonia (c 40; southern Central America, South America, with their highest diversity in the Andes), Forgesia (1; F. racemosa; Réunion), Valdivia (1; V. gayana; Valdivia Province in Chile). – Southern Central America to southernmost South America, Réunion, southeastern and southwesternmost Australia, Tasmania. Usually trees or shrubs (rarely annual herbs). Phellogen in Escallonia often deeply seated. Nodes usually 3:3 (sometimes 1:1 or 5:5). Cells of glandular heads with radially arranged walls. Leaves spiral, with usually supervolute (sometimes conduplicate) ptyxis. Petiole vascular bundle transection arcuate. Stomata anomocytic. Leaf margin usually serrate, with glandular teeth and two accessory veins (leaf apex in Tribeles with three small teeth). Petals in Escallonia connate. Anthers often longer than connective. Placentoid sometimes present. Endoaperture in Eremosyne complex. Tectum in Eremosyne and Tribeles incomplete, in Tribeles rugulate-reticulate with disrupted muri. Stigma in Tribeles subclavate to somewhat trilobate. Ovules usually unitegmic (in Tribeles bitegmic). Integument five to eight cell layers thick. Micropyle often elongated. Seeds in Tribeles long attached to central columella of open ripe coriaceous capsule. Mesotesta and/or endotesta usually persistent. Embryo sometimes elongated. n = 12 (Escallonia). Both copies of nuclear gene rpb2 present in Escallonia. Flavonols, Route I secoiridoids and Route II decarboxylated iridoids present.

Escalloniaceae are probably sister-group to the clade [Bruniales+[Araliales+[Paracryphiales+Dipsacales]]].

The results from the different molecular analyses of Escalloniaceae are contradictory. Polyosma was recovered as sister-group to Quintinia (Paracryphiaceae), with high bootstrap support, when using mitochondrial DNA data in the 17-gene analyses by Soltis & al. (2011). On the other hand, when mtDNA data were excluded, Polyosma was placed in Escalloniaceae, also with high bootstrap support. Horizontal transfer of mitochondrial genes may explain these results, according to Soltis & al. (2011). Moreover, Polyosma was sister to the remaining Escalloniaceae in the analysis by Lundberg (2001). Finally, it was closely allied to Anopterus and Tribeles in the investigation by Sede & al. (2013), whereas Eremosyne was sister to the remaining Escalloniaceae. – Polyosma consists of trees. Phellogen subepidermal. Pericycle with sclereids. Nodes 1:1, unilacunar with a single leaf trace. Hairs unicellular. Leaves opposite. Leaf margin often serrate. Stipules absent. Inflorescence axillary raceme. Epigyny. Flowers with long buds. Sepals four, connate. Petals four, with valvate aestivation, free (primarily or secondarily?), relatively narrow. Pollen grains triporate. Pistil composed of two connate carpels. Ovary inferior. Stigma capitate, bilobate. Placentation intrusively parietal. Ovules numerous per carpel. Integument up to ten cell layers thick. Parietal tissue approx. one cell layer thick? Megasporangial base massive. Megasporocytes sometimes several. Fruit a single-seeded drupe. Testa up to ten cell layers thick. Endosperm thick-walled, rich in starch. Embryo undifferentiated. n = ? Iridoids present. Aluminium accumulated in at least some species.

Phylogeny of Escalloniaceae based on DNA sequence data (Lundberg 2001).

Phylogeny (majority-rule consensus tree) of Escalloniaceae based on DNA sequence data (Sede & al. 2013).


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