Description

Key Characters:

Growth Form: Annual, biennial, or perennial herbs, occasionally shrubs.

Stems:

Roots:

Leaves: Leaves simple. Alternate or rarely opposite. Margins entire to lobed or pinnately divided. Petiolate, sessile, or subsessile. Stipules absent.

Flowers: Flowers in usually bractless, terminal racemes, occasionally solitary. Flowers bisexual (perfect), actinomorphic or rarely slightly irregular. Calyx of 4 sepals, deciduous, erect, usually oblong, sometimes the inner 2 with gibbous bases that hold the nectar. Corolla of 4 petals, rarely absent, yellow, white, or lavender, entire to emarginate, rarely lobed or fimbriate, usually with an elongate claw. Stamens (2–4)6(–16), tetradynamous, the inner 4 usually in pairs, sometimes connate at base in pairs; anthers dithecal, opening by longitudinal slits. Ovary superior, 2(4?)-carpellate, usually 2-celled by means of a false, but usually complete septum, rarely 1-celled, sessile or rarely stipitate; ovules 1 to numerous, borne on parietal placentas on replum margin at periphery of ovary wall, campylotropous or occasionally anatropous; style 1 or occasionally absent; stigma capitate or rarely decurrent, entire or 2-lobed.

Fruit: Capsules divided into 2 cells by the usually thin and membranous septum; elongate (at least 3 times as long as wide) and referred to as a silique; or short (less than 3 times a long as wide) and referred to as a silicle; dehiscent from the base upward; exposing the septum; sometimes fruit indehiscent or dehiscent and jointed between the seeds; ± breaking up at maturity. Seeds 1 to numerous; often becoming mucilaginous when wet; endosperm essentially absent.

Ploidy:

Habitat: Occurring primarily in cool to warm temperate regions of both hemispheres; with especially large numbers in arid climates such as the Mediterranean region; western North America; and temperate South America.

Elevation Range: