The families of flowering plants

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L. Watson and M. J. Dallwitz

Epacridaceae R. Br.

~ Ericaceae-Styphelioideae.

Including Prionotidaceae (Prionotaceae) Hutch., Stypheliaceae Horan.; excluding Wittsteinia.

Habit and leaf form. Small trees, or shrubs (often ‘ericoid’); leptocaul, or pachycaul. Helophytic to xerophytic (mostly on acid substrates). Leaves evergreen; minute to medium-sized; alternate; spiral, or four-ranked; flat, or rolled; ‘herbaceous’, or leathery; imbricate, or not imbricate; petiolate to sessile; sheathing (Cosmelia, Andersonia, Sprengelia, Dracophyllum, Richea Sphenotoma — in the first three, associated with a very peculiar mode of leaf abscission, resulting in sloughing away of the outer parts of the stem), or non-sheathing. Leaf sheaths when present, with free margins. Leaves simple. Lamina entire; one-veined, or palmately veined (commonly), or parallel-veined (genuinely so in Richeoideae, but only ostensibly so in Cosmelieae where the parallel veins in the lamina originate palmately from a single leaf trace); cross-venulate, or without cross-venules. Leaves exstipulate. Lamina margins flat, or revolute.

Leaf anatomy. The leaf lamina dorsiventral. Stomata mainly confined to one surface (then usually abaxial, but sometimes adaxial only in Leucopogon), or on both surfaces (commonly so in Andersonia and Dracophyllum); anomocytic (most Epacridoïdeae), or paracytic (Richeoïdeae), or cyclocytic (some Epacridoideae-Cosmelieae). Hairs absent, or present (but then inconspicuous, infrequent, and uniform, by contrast with the diversity exhibited by the Ericaceae); if present,exclusively eglandular; unicellular. Unicellular hairs simple. Complex hairs absent. Adaxial hypodermis present, or absent. Lamina without secretory cavities. The mesophyll containing calcium oxalate crystals. The mesophyll crystals druses and solitary-prismatic. Midrib usually not conspicuous. Main veins vertically transcurrent, or embedded. Minor leaf veins without phloem transfer cells (Leucopogon).

Axial (stem, wood) anatomy. Secretory cavities absent. Cork cambium present to absent (in that a distinct phellogen is not always clearly defined); initially deep-seated. Nodes unilacunar (mostly), or tri-lacunar to multilacunar (Dracophyllum, Richea). Primary vascular tissue in a cylinder, without separate bundles; collateral. Internal phloem absent. Cortical bundles absent. Medullary bundles absent. Secondary thickening developing from a conventional cambial ring. Primary medullary rays narrow, or mixed wide and narrow.

The wood diffuse porous. The vessel end-walls scalariform and simple, or simple. The vessels without vestured pits; with spiral thickening, or without spiral thickening. The axial xylem with tracheids; with fibre tracheids (typically), or without fibre tracheids (?); with libriform fibres, or without libriform fibres; including septate fibres (rarely), or without septate fibres. The fibres with spiral thickening, or without spiral thickening. The parenchyma apotracheal (sometimes sparse). ‘Included’ phloem absent. The wood not storied.

Reproductive type, pollination. Unisexual flowers absent. Plants hermaphrodite (nearly always). Pollination entomophilous, or ornithophilous; mechanism conspicuously specialized (with Acrotriche serrulata exhibiting passive pollen presentation via corolla hairs), or unspecialized.

Inflorescence, floral, fruit and seed morphology. Flowers solitary, or aggregated in ‘inflorescences’. Inflorescences when flowers aggregated, terminal, or axillary. Flowers bracteate; bracteolate; small to medium-sized, or minute (rarely); fragrant, or odourless; regular; mostly (4–)5 merous; cyclic; tetracyclic. Free hypanthium absent. Hypogynous disk present (usually), or absent (e.g. Sprengelia); intrastaminal; of separate members, or annular.

Perianth with distinct calyx and corolla; 8 (Oligarrhena), or 10; 2 whorled; isomerous. Calyx 4 (Oligarrhena only), or 5; 1 whorled; polysepalous; regular; persistent; imbricate. Corolla 4 (Oligarrhena only), or 5; 1 whorled; polypetalous, or gamopetalous. Corolla lobes markedly shorter than the tube to markedly longer than the tube. Corolla imbricate, or valvate (or induplicate-valvate in Needhamiella only), or contorted (Lysinema); regular; green, or white, or red, or pink, or purple, or blue, or yellow (rarely, but exemplified in the peculiar monotypic, Oligarrhena); persistent, or deciduous.

Androecium (4–)5, or 2 (Oligarrhena). Androecial members free of the perianth (Andersonia, Sprengelia, Lysinema, Prionotes, Lebetanthus), or adnate (to the corolla); all equal; free of one another; 1 whorled. Androecium exclusively of fertile stamens. Stamens (4–)5 (usually), or 2 (Oligarrhena); inserted when epipetalous, midway down the corolla tube, or in the throat of the corolla tube; reduced in number relative to the adjacent perianth to isomerous with the perianth; oppositisepalous (hypogynous or epipetalous); alternating with the corolla members; laminar, or filantherous, or with sessile anthers. Anthers basifixed, or adnate; becoming inverted during development, their morphological bases ostensibly apical in the mature stamens; non-versatile; dehiscing via longitudinal slits (usually by a single median slit, rarely by two — e.g. Conostephium); finally introrse (inverting during development, cf. Ericaceae); unilocular (usually), or bilocular; bisporangiate; unappendaged (but their apices sometimes sterile). Endothecium not developing fibrous thickenings. Anther epidermis persistent. Microsporogenesis simultaneous. Tapetum glandular. Pollen shed in aggregates (usually), or shed as single grains; without viscin strands; when aggregated, in diads, or in triplets, or in tetrads (in Styphelioideae often shed as tetrads with 1–3 abortive members). Pollen grains aperturate; 3 aperturate, or 4–10 aperturate; porate (commonly), or colporate (commonly), or foraminate, or rugate; not lophate; 3-celled.

Gynoecium (2–)5(–10) carpelled (consistently 2 only in Oligarrhena and Needhamiella). The pistil (1–)5(–10) celled. Gynoecium syncarpous; eu-syncarpous; superior. Ovary (1–)5(–10) locular. Gynoecium stylate. Styles 1; attenuate from the ovary (Styphelieae, Oligarrhena, Needhamiella), or from a depression at the top of the ovary (Cosmelieae, Epacrideae, Richeoideae); apical (usually), or ‘gynobasic’ (Archeria). Stigmas 1; truncate, or clavate, or capitate. Placentation axile, or axile to apical (e.g. Leucopogon), or basal to axile (Archeria). Ovules 1–50 per locule (i.e. to ‘many’); pendulous (usually), or ascending (Archeria); non-arillate; anatropous; unitegmic; tenuinucellate. Endothelium differentiated. Embryo-sac development Polygonum-type. Polar nuclei fusing prior to fertilization. Antipodal cells formed; 3; proliferating (e.g. in Leucopogon), or not proliferating. Synergids with filiform apparatus. Endosperm formation cellular. Endosperm haustoria present; chalazal and micropylar (usually, but the former rudimentary in Brachyloma), or micropylar (no chalazal haustorium in Styphelia). Embryogeny caryophyllad to solanad.

Fruit fleshy, or non-fleshy; dehiscent (Cosmelieae, Epacrideae, Richeoideae), or indehiscent (Styphelieae, Oligarrhena, Needhamiella); a capsule (when dehiscent), or a drupe. Capsules loculicidal. The drupes with separable pyrenes, or with one stone. Seeds endospermic. Endosperm oily. Seeds wingless. Embryo well differentiated. Cotyledons 2. Embryo straight.

Seedling. Germination phanerocotylar.

Physiology, phytochemistry. C3. Anatomy non-C4 type (widely examined by L.W.). Cyanogenic, or not cyanogenic. Alkaloids present (rarely), or absent. Arbutin absent. Iridoids detected; ‘Route I’ type (normal). Saponins/sapogenins absent. Proanthocyanidins present; cyanidin, or cyanidin and delphinidin. Flavonols present; quercetin, or kaempferol and quercetin. Ellagic acid absent (3 genera). Ursolic acid present. Aluminium accumulation not found.

Geography, cytology. Temperate to tropical. Indonesia to New Zealand, Hawaii to southern South America, but mainly Australia. X = 4–14.

Taxonomy. Subclass Dicotyledonae; Tenuinucelli. Dahlgren’s Superorder Corniflorae; Ericales. Cronquist’s Subclass Dilleniidae; Ericales. APG 3 core angiosperms; core eudicot; Superorder Asteranae; Order Ericales (as a subfamily of Ericaceae).

Species 400. Genera 31; Acrotriche, Andersonia, Archeria, Astroloma, Brachyloma, Choristemon, Coleanthera, Conostephium, Cosmelia, Cyathodes, Cyathopsis, Decatoca, Dracophyllum, Epacris, Lebetanthus, Leucopogon, Lissanthe, Lysinema, Melichrus, Monotoca, Needhamiella, Oligarrhena, Pentachondra, Prionotes, Richea, Rupicola, Sphenotoma, Sprengelia, Styphelia, Trochocarpa, Woolsia.

General remarks. Submerged of late in the Ericaceae by pedantic nomenclatural interpretation of cladistic theories, this exclusively southern hemisphere assemblage differs from the traditional, sensu stricto version of that family almost absolutely in the tetracyclic flowers and non-versatile, bisporangiate stamens; the general glabrosity of this (“the most glabrous of families”) stands in remarkable contrast to the spectacular range of hair types found in abundance in Ericaceae; particular states of 78 characters included in the present compilation (including very conspicuous vegetative, floral and pollen-morphological features) are either confined to or are very rare in the one family or the other; and arbutin, andromedotoxin and inulin seem not to have been found in Epacridaceae. For classificatory analyses, see Watson 1967; Watson, Williams and Lance 1967.

Illustrations. • Technical details: Epacris, Leucopogon, Archeria. • Acrotriche epacridis: habit and flowers (photo). • Andersonia sprengelioides: habit (photo). • Andersonia sprengelioides: flowers (photo). • Sprengelia, Andersonia - floral and (peculiar) leaf morphology.. • Astroloma pinifolium: Bot. Reg. 218, 1817. • Cosmelia rubra: Bot. Reg. 1822, 1836. • Epacris impressa, var.: Bot. Reg. 1839, 19. • Lissanthe sapida: Bot. Reg. 1275, 1829. • Leucopogon vericillatus: habit (photo). • Sphenotoma gracile: inflorescence. • Sphenotoma gracile: vegetative. • Sphenotoma gracile: habitat. • Styphelia longifolia: Bot. Reg. 24, 1815. • Styphelia, Astroloma, Leucopogon - exemplifying ‘false bracts’ (modified inflorescence internodes). • Pollen: Astroloma, Coleanthera, Conostephium, Croninia, Styphelia. • Pollen: Astroloma, Brachyloma, Melichrus, Oligarrhena. • Pollen: Acrotriche, Cyathodes, Pollen: Cyathopsis, Lissanthe, Monotoca, Pentachondra. • Pollen: Leucopogon (8 species), Needhamiella.

Quotations

Squarrosely cushioning the rocks
About King George’s Sound
(anon - of Andersonia sprengelioides)


This description is offered for casual browsing only. We strongly advise against extracting comparative information from it. This is much more easily achieved using the interactive key, which allows access to the character list, illustrations, full and partial descriptions, diagnostic descriptions, differences and similarities between taxa, lists of taxa exhibiting or lacking specified attributes, distributions of character states within any set of taxa, geographical distribution, genera included in each family, and classifications (Dahlgren; Dahlgren, Clifford, and Yeo; Cronquist; APG).

Cite this publication as: ‘Watson, L., and Dallwitz, M.J. 1992 onwards. The families of flowering plants: descriptions, illustrations, identification, and information retrieval. Version: 19th October 2013. http://delta-intkey.com’.

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