Habit and leaf form. Herbs. Annual, or perennial. Leaves cauline. Stem internodes solid. To 0.05–0.4 m high. Mesophytic. Leaves small to medium-sized; alternate; spiral; ‘herbaceous’; subsessile; non-sheathing; simple; epulvinate. Leaf blades entire; elliptic (narrowly), or ovate to linear; one-veined, or pinnately veined; cross-venulate. Leaves without stipules. Leaf blade margins entire (almost). Leaves without a persistent basal meristem. Leaf anatomy. Hairs present (usually), or absent; glandular hairs absent; complex hairs present (medifixed), or absent. Branched hairs absent. Complex hairs ‘reduced-stellate’ — i.e. two armed. 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, or in corymbs (some doubt about this). The terminal inflorescence unit racemose. Flowers pedicellate; ebracteate; ebracteolate; small; fragrant; more or less regular; 2 merous; cyclic. Floral receptacle with neither androphore nor gynophore. Free hypanthium absent. Hypogynous disk present; extrastaminal to intrastaminal (the lateral glands alongside the stamens, the medians outside); of separate members. Perianth with distinct calyx and corolla; 8; 3 -whorled (K 2+2, C 4). Calyx present; 4; 2 -whorled; polysepalous; spreading; decussate; regular; not persistent. Corolla present; 4; 1 -whorled; alternating with the calyx; polypetalous; imbricate; regular; white, or pink, or purple (or mauve). Petals clawed. Androecial members definite in number. Androecium 6. Androecial members branched (in that the inner whorl of 4 is derived from only 2 primordia); free of the perianth; markedly unequal; free of one another; 2 -whorled (2+4). Androecium exclusively of fertile stamens. Stamens 6 (2 outer, 4 inner); tetradynamous; all more or less similar in shape; hypogynous, on receptacle, outer stamen lateral. Filaments not appendiculate. Anthers basifixed; non-versatile; dehiscing via longitudinal slits; introrse; unilocular to bilocular; tetrasporangiate; unappendaged. Pollen shed as single grains. Gynoecium 2 carpelled. The pistil 2 celled. Gynoecium syncarpous; eu-syncarpous; superior. Ovary plurilocular; 2 locular. Locules secondarily divided by ‘false septa’. Gynoecium transverse. Ovary sessile. Gynoecium stylate. Styles 1; apical. Stigmas 1 (or 2); 1 - lobed (capitate); capitate. Placentation parietal. Ovules 1–5 per locule; with ventral raphe; non-arillate; anatropous.
Fruit and seed features. Fruit 3–4 mm long; non-fleshy; dehiscent; a silicula. Capsules valvular. Fruit 2 celled; 2 seeded. Seeds 1 per locule. Seeds scantily endospermic, or non-endospermic; not mucous; compressed; small to medium sized; narrowly winged. Embryo well differentiated. Cotyledons 2; accumbent. Embryo bent.
Physiology, biochemistry. Mustard-oils present.
Special features. Fruit body with no clear differentiation into valve and beak regions. Replum present and complete; broad. Fruit bilaterally compressed; compressed parallel with the septum. The inner (lateral) pair of sepals not noticeably saccate. Petals not peculiarly elongated as in Stenopetalum. Nectariferous glands lateral and median. Valves of the fruit neither winged nor keeled; conspicuously longitudinally veined; longitudinally 1 veined. Fruit not apically notched.
Etymology. From the Latin for "small pod".