Homalosciadium Domin

Scientific Description

Family Apiaceae.

Habit and leaf form. Small herbs; bearing essential oils, or without essential oils (?); resinous, or not resinous (?). Annual; 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; peltate, or not peltate (?); pulvinate, or epulvinate (?). Leaf blades dissected; obovate (in outline); deeply divided into 3 segments, each with 2 or 3 lobes; pinnately veined, or palmately 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 simple. The terminal inflorescence unit cymose, or racemose. Inflorescences axillary; sessile; with involucral bracts, or without involucral bracts (?); pseudanthial, or not pseudanthial (?). Flowers bracteate. Bracts linear. Flowers small; regular to somewhat irregular (?); 5 merous (except for the gynoecium); cyclic; tetracyclic, or tricyclic. Free hypanthium absent. Perianth petaline (the calyx present only as a minute inconspicuous ring); 5; 1 -whorled; green. Corolla 5; 1 -whorled; polypetalous; valvate; unequal but not bilabiate, or regular (?); green. Petals obovate. 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 circular in outline; 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 into a disc-like 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 (flattened, the dorsal rib prominent and acute). 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. Endemic to Australia. Australian states and territories: Western Australia.