Centella L.

Scientific Description

Family Apiaceae.

Habit and leaf form. Creeping herbs; bearing essential oils, or without essential oils (?); resinous, or not resinous (?). Perennial; plants with a basal concentration of leaves, or with neither basal nor terminal concentrations of leaves; stoloniferous. Hydrophytic, or helophytic. Leaves small to medium-sized; alternate (or clustered); ‘herbaceous’; petiolate. Petioles sheathing at base, with translucent 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 entire; cordate, reniform or circular; pinnately veined, or palmately veined (?). Leaves with stipules, or without stipules. Leaf blade margins crenate. Leaves 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, or hermaphrodite and functionally male (sometimes, in the same inflorescence). Unisexual flowers absent (usually), or present. Plants hermaphrodite, or andromonoecious. Entomophilous.

Inflorescence and flower features. Flowers aggregated in ‘inflorescences’; in umbels. Inflorescences simple. The terminal inflorescence unit cymose, or racemose (?). Inflorescences axillary; with involucral bracts, or without involucral bracts. Flowers pedicellate; bracteate, or ebracteate. Bracts few. Flowers small; regular; 5 merous (except for the gynoecium); cyclic; tetracyclic, or tricyclic. Free hypanthium absent. Perianth with distinct calyx and corolla (but the calyx very reduced), or petaline; 5, or 10; 2 -whorled, or 1 -whorled; isomerous; white, or red, or pink, or purple. Calyx present to vestigial, or absent; when detectable, 5; 1 -whorled. Corolla 5; 1 -whorled; polypetalous; imbricate; regular; white, or red, or pink, or purple. Petals broadly ovate. Androecium 5. Androecial members free of the perianth; all equal; 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. Fertile gynoecium present, or absent (male flowers). 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 (with 4–6 prominent ribs connected by smaller ribs). 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, Queensland, New South Wales, Victoria, Australian Capital Territory, and Tasmania.