Alocasia (Schott) G.Don

Scientific Description

Family Araceae.

Habit and leaf form. Massive trees, or herbs; laticiferous. Plants unarmed. Perennial; plants with a basal concentration of leaves, or with neither basal nor terminal concentrations of leaves; with short subterranean tubers or thick aerial stems. Self supporting (to decumbent or creeping). Pachycaul. Helophytic, or mesophytic. Heterophyllous, or not heterophyllous. Leaves small to very large; alternate; spiral; petiolate (appearing conventionally ‘petiolate’ when the sheath shed); sheathing (the sheath membranous). Leaf sheaths with free margins. Leaves with ‘normal’ orientation; simple; peltate (occasionally, especially in juveniles), or not peltate. Leaf blades dissected, or entire; pinnately veined; cross-venulate; cordate, or hastate, or sagittate. Leaves ligulate, or eligulate. Axillary scales present, or absent. Leaves without a persistent basal meristem. Vegetative anatomy. Plants without silica bodies. Leaf anatomy. Guard-cells not ‘grass type’. Hairs present, or absent. Stem anatomy. Secondary thickening absent. Roots. Roots with velamen, or without velamen.

Reproductive type, pollination. Fertile flowers functionally male and functionally female. Unisexual flowers present. Plants monoecious. The unisexual flowers aggregated in different parts of the same inflorescence. Anemophilous, or entomophilous. Pollination mechanism conspicuously specialized, or unspecialized.

Inflorescence and flower features. Flowers aggregated in ‘inflorescences’; in spikes. Inflorescences usually paired. The terminal inflorescence unit seemingly racemose. Inflorescences scapiflorous, or not scapiflorous; apparently lateral; consisting of specialised spikes (‘spadices’), the spadix with naked female flowers below, then a zone of tubercular sterile flowers, then a zone of elongate male flowers of fused stamens, and finally a tapering sterile ‘appendix’; pseudanthial; spatheate (spathe with clearly defined basal convolute tube and upper reflexed to spreading to cowl-like lamina, separated by a constriction; lower part persistent, the upper becoming soft and either wasting away or persistent). Flowers ebracteate; ebracteolate; small (numerous); (these or the spadix) fragrant, or malodorous; cyclic. Perianth absent. Fertile stamens present, or absent (when female). Androecium 4–10(–36). Androecial members coherent (fused into mutually free synandria). Androecium exclusively of fertile stamens. Stamens 4–10(–36). Anthers cohering; basifixed; non-versatile; dehiscing via pores, or dehiscing via longitudinal slits; extrorse; bisporangiate, or tetrasporangiate. Pollen shed in aggregates, or shed as single grains. Fertile gynoecium present, or absent (when male). Gynoecium 1–4 carpelled. The pistil 1 celled (or apically incompletely 4-septate). Gynoecium monomerous, or syncarpous; of one carpel, or synstylovarious to eu-syncarpous; superior. Carpel apically stigmatic. Ovary unilocular; 1 locular. Gynoecium shortly stylate, or non-stylate. Styles apical. Stigmas button-like to stellate; wet type, or dry type; papillate, or non-papillate; Group II type. Placentation basal. Ovules in the single cavity several; pendulous, or horizontal, or ascending; sub- orthotropous to anatropous.

Fruit and seed features. Fruit fleshy; orange to red; an aggregate, or not an aggregate. The fruiting carpel when monomerous, indehiscent; drupaceous, or baccate, or nucular. Fruit indehiscent; a berry (the infructescence enclosed by the lower part of the spathe which is longitudinally dehiscent at maturity). Dispersal unit the fruit, or the inflorescence. Fruit 1-several-seeded. Seeds endospermic. Endosperm oily (and starchy). Perisperm absent. Seeds with starch. Cotyledons 1. Embryo straight (linear). Seedling. Hypocotyl internode present, or absent. Mesocotyl absent. Seedling collar not conspicuous. Cotyledon hyperphyll compact; assimilatory, or non-assimilatory. Coleoptile absent. Seedling non-macropodous. First leaf dorsiventral. Primary root ephemeral.

Physiology, biochemistry. Photosynthetic pathway: C₃.

Geography, cytology, number of species. Native of Australia. Not endemic to Australia. Australian states and territories: Western Australia, Queensland, and New South Wales.

Additional characters Leaves not solitary.