Habit and leaf form. Herbs. Plants succulent to non-succulent. Annual. Young stems ribbed. Stem internodes solid. Rhizomatous. Mesophytic, or xerophytic. Leaves alternate; spiral; somewhat fleshy, or leathery; petiolate, or subsessile, or sessile; non-sheathing; simple; epulvinate. Leaf blades entire; linear, or lanceolate, or oblanceolate; narrowly linear; one-veined, or pinnately veined. Leaves inconspicuously with stipules. Stipules interpetiolar; scaly; caducous (sometimes), or persistent. Leaf blade margins entire. Leaf anatomy. Hairs absent. Extra-floral nectaries absent.
Reproductive type, pollination. Fertile flowers hermaphrodite. Unisexual flowers absent. Plants hermaphrodite.
Inflorescence and flower features. Flowers aggregated in ‘inflorescences’; in racemes. The terminal inflorescence unit cymose, or racemose. Inflorescences terminal. Flowers pedicellate (slender); bracteate (1 at base of pedicel subtends each flower); bracteolate (2 subtend each flower); regular; 5 merous; cyclic; tetracyclic. Free hypanthium present; shallow. Hypogynous disk present (lining the calyx tube). Perianth with distinct calyx and corolla; 10; 2 -whorled; isomerous. Calyx present; 5; 1 -whorled; gamosepalous (connate towards the base); deeply blunt-lobed; imbricate; regular, or unequal but not bilabiate; green (A), or cream (KP). Calyx lobes narrowly triangular. Corolla present; 5; 1 -whorled; polypetalous; imbricate; unequal but not bilabiate, or regular; white and pink (with a pink throat). Petals narrowly obovate; clawed. Androecial members definite in number. Androecium 5. Androecial members free of the perianth; all equal; free of one another; 1 -whorled. Androecium exclusively of fertile stamens. Stamens 5; all more or less similar in shape; isomerous with the perianth; oppositisepalous (on the margin of the disc). Anthers dehiscing via longitudinal slits; tetrasporangiate; appendaged. The anther appendages apical. Gynoecium 5 carpelled. The pistil 5 celled. Carpels isomerous with the perianth. Gynoecium syncarpous; synstylovarious, or eu-syncarpous; superior. Ovary plurilocular; 5 locular. Gynoecium stylate. Styles 1; attenuate from the ovary, or from a depression at the top of the ovary; apical. Stigmas 1, or 5; 5 - lobed (A). Placentation axile to basal. Ovules 1 per locule; ascending; apotropous; with ventral raphe; anatropous.
Fruit and seed features. Fruit non-fleshy; a schizocarp. Mericarps comprising nutlets (cocci). Fruit 5 celled; about 4 seeded, or 5 seeded. Seeds endospermic. Endosperm oily. Cotyledons 2. Embryo straight.
Etymology. After John Macgregor (1828–84), solicitor, MLA of Victoria.