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The families of flowering plants.                                                                                                                                                                

Epacridaceae R. Br.

                        

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~Ericaceae

IncludingPrionotidaceae (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. Stomata mainly confined to one surface, or on both surfaces; anomocytic, or cyclocytic. Hairs usually absent.

Lamina dorsiventral; without secretory cavities. Midrib usually not conspicuous. Main veins vertically transcurrent, or embedded. Minor leaf veins without phloem transfer cells (Leucopogon).

Stem anatomy. Secretory cavities absent. Cork cambium present; initially deep-seated. Nodes unilacunar (mostly), or tri-lacunar to multilacunar (Dracophyllum, Richea). Primary vascular tissue centrifugal. Cortical bundles absent. Medullary bundles absent. Internal phloem absent. Secondary thickening developing from a conventional cambial ring. ‘Included’ phloem absent. Xylem with tracheids; with vessels. Vessel end-walls scalariform and simple, or simple. Primary medullary rays mixed wide and narrow. Wood parenchyma apotracheal (sometimes sparse).

Reproductive type, pollination. Unisexual flowersabsent. 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 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.

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

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 synonym 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. 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.
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