Habit and leaf form. Slender, erect 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 (lower leaves), or sessile (upper leaves); 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; 3-pinnatisect or several times ternate; pinnately veined. Leaves with stipules, or 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; without involucral bracts (usually), or with involucral bracts; pseudanthial, or not pseudanthial (?). Flowers pedicellate; ebracteate (usually), or bracteate; ebracteolate (usually), or bracteolate; small; regular to somewhat irregular (?); 5 merous (except for the gynoecium); cyclic; tetracyclic. Free hypanthium absent. Perianth with distinct calyx and corolla (but the calyx very reduced); 10; 2 -whorled; isomerous; white. Calyx present to vestigial; when detectable, 5; 1 -whorled. Corolla 5; 1 -whorled; polypetalous; valvate; unequal but not bilabiate, or regular; white. Petals broadly ovate to elliptic. Corolla members entire (often shortly apiculate). 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 into one or two stylopodes 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; not hairy (or rarely shortly bristly); a schizocarp. Mericarps 2 (with 5 prominent 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. Adventive. Australian states and territories: Western Australia, South Australia, Northern Territory, Queensland, New South Wales, and Victoria.
Additional characters Petals inflexed (sometimes), or not inflexed.