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Apium L.
Species plantarum 2:264 (1753)

Name Status: Current

Scientific Description
H.R. Coleman, Friday 3 October 2008

Family Apiaceae.

Habit and leaf form. Erect or prostrate herbs; bearing essential oils, or without essential oils (?); resinous, or not resinous (?). Annual, or biennial, or perennial; plants with a basal concentration of leaves, or with neither basal nor terminal concentrations of leaves (?). Helophytic, or mesophytic. Leaves small to medium-sized; alternate; ‘herbaceous’; petiolate; more or less sheathing. Leaf sheaths with free margins. Leaves gland-dotted, or not gland-dotted (?); aromatic, or foetid, or without marked odour (?); simple, or compound; peltate, or not peltate (?); pulvinate, or epulvinate (?); when compound, pinnate. Leaf blades when simple, dissected; pinnately or ternately divided, the segments often further divided; pinnately veined. Leaves without stipules; without a persistent basal meristem. Leaf anatomy. Hairs absent. Stem anatomy. Nodes multilacunar, or tri-lacunar (?). Secondary thickening developing from a conventional cambial ring, or anomalous (?); from a single cambial ring.

Reproductive type, pollination. Fertile flowers hermaphrodite. Unisexual flowers absent. Plants hermaphrodite. Entomophilous.

Inflorescence and flower features. Flowers aggregated in ‘inflorescences’; in umbels. Inflorescences compound. The terminal inflorescence unit cymose, or racemose (?). Inflorescences leaf-opposed; usually without ray bracts. Flowers bracteate, or ebracteate; ebracteolate; small; regular to somewhat irregular (?); 5 merous (except for the gynoecium); cyclic; tricyclic. Free hypanthium absent. Perianth petaline; 5; 1 -whorled; white. Corolla 5; 1 -whorled; polypetalous; valvate; unequal but not bilabiate, or regular (?); white. Petals ovate. Corolla members entire. Androecium 5. Androecial members free of the perianth; all equal to markedly unequal (?); free of one another; 1 -whorled. Androecium exclusively of fertile stamens. Stamens 5; isomerous with the perianth; oppositisepalous; inflexed in bud. Anthers dehiscing via longitudinal slits; introrse; tetrasporangiate. Gynoecium 2 carpelled. The pistil 2 celled. Gynoecium syncarpous; synovarious; inferior. Ovary plurilocular; 2 locular. Gynoecium median. Epigynous disk present. Gynoecium stylate. Styles 2; free to partially joined (their bases thickened to form a short-conical or depressed stylopodium crowning the ovary); apical. Stigmas wet type; non-papillate; Group IV type. Placentation axile, or apical (?). Ovules 1 per locule, or 2 per locule (usually two, but one abortive ?); pendulous; epitropous; non-arillate; anatropous.

Fruit and seed features. Fruit non-fleshy; a schizocarp. Mericarps 2 (united facially, ribbed). Seeds 1 per mericarp. Seeds endospermic. Endosperm oily. Embryo well differentiated. Cotyledons 2. Embryo achlorophyllous; straight. Seedling. Germination phanerocotylar.

Physiology, biochemistry. Aluminium accumulation not found. Photosynthetic pathway: C₃.

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

Economic uses, etc. Important food plant (celery).

Additional characters Petals inflexed.

Keys to Apium L.