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FAMILY DESCRIPTION

Brassicaceae Burnett, Outlines Bot. 1123. 1835.
Cruciferae A. L. de Jussieu, Gen. Pl. 237. 1789.

Brief Description

Herbs or rarely subshrubs or shrubs, glabrous or with simple or branched trichomes. Leaves exstipulate, mostly simple, often alternate. Flowers hypogynous, mostly actinomorphic, perfect; sepals 4, often free; petals 4, forming cruciform corolla, rarely absent; stamens mostly 6, often tetradynamous (inner 4 longer than outer 2); nectar glands subtending or surrounding bases of at least lateral stamens; pistil 2-carpellate, often two locular, placentation parietal. Fruits often capsule, dehiscent or indehiscent, often with a false septum. Seeds without endosperm; embryo large, folded or curved.

Detailed Description

Herbs, annual, biennial, or perennial, sometimes subshrubs or shurbs, very rarely lianas (Cremolobus, Heliophila, Lepidium) or small trees (Farsetia); with a pungent watery juice rich in glucosinolates (mustard oil glucosides) and with idioblasts containing enzyme myrosinase; taprooted or with few to many-branched and slender or woody caudex, sometimes with slender or tuberous rhizomes, rarely stoloniferous; terrestrial or rarely submerged aquatics, without or rarely with multicellular glandular papillae or tubercles. Trichomes unicellular, simple, stalked or sessile, 2-many forked, stellate, dendritic, or malpighiaceous (medifixed, bifid, appressed), rarely peltate and scalelike (Physaria), eglandular. Stems erect, ascending, or prostrate, herbaceous or rarely woody, leafy or leafless, sometimes absent (Idahoa). Leaves exstipulate or rarely with tiny, stipule-like glands at base of petioles and pedicels, simple, entire or variously dissected, rarely compound (Cardamine) and trifoliolate or pinnatey, palmate, or bipinnate; stomata typically anisocytic, rarely mixed with other types; basal leaves rosulate or not, persistent or withered by flowering time; cauline leaves almost always alternate, rarely opposite or whorled (Cardamine), petiolate or sessile, auriculate or not, sometimes absent. Inflorescences racemes, corymbs, or panicles, terminal or rarely axillary (some Lepidium), ebracteate or less frequently bracteate, sometimes flowers solitary on pedicels originating from axils of rosette leaves (Leavenworthia, Pegaeophyton); pedicels persistent or caducous with fruit, variously oriented, rarely geotropic (Geococcus, Morisia). Flowers hypogynous, actinomorphic or rarely zygomorphic (Iberis, some Streptanthus), bisexual or rarely unisexual and plants dioecious (Lepidium sisymbrioides; New Zealand). Sepals 4, in 2 decussate pairs (1 pair lateral and 1 median), free or rarely united (some spp. of Brayopsis, Sisymbrium, and Solms-laubachia), not saccate or lateral (inner) pair saccate or rarely spurred (Chamira), sometimes both pairs saccate, caducous or rarely persistent, erect, ascending, spreading, or reflexed, forming tubular, campanulate, or urceolate calyx. Petals 4, alternate with sepals, arranged in the form of a cross (cruciform; hence the earlier family name Cruciferae) or rarely into adaxial and abaxial pairs, imbricate or contorted in bud or rarely circinate (some Matthiola), rarely rudimentary or absent (some Lepidium), differentiated or not into blade and claw, basally unappendaged or rarely appendaged; blade entire or emarginated, rarely 2-fid (Berteroa), pinnatifid (Schizopetalon), fimbriate (Ornithocarpa), or filiform (Stenopetalum), sometimes reduced and much smaller than well-developed claws (Streptanthus). Stamens mostly 6, in 2 whorls, tetradynamous (lateral (outer) pair shorter than median (inner) 2 pairs), rarely equal in length (Stanleya, Warea) or in 3 pairs of unequal length (Streptanthus, Camelina), sometimes stamens 2 or 4 (Lepidium), very rarely 8–24 (Megacarpaea polyandra); filaments slender or winged, appendaged, or toothed (Alyssum), median pairs free or rarely united ; anthers dithecal, dehiscing by longitudinal slits; pollen grains mostly 3-colpate, sometimes 4–10-colpate (tribe Physarieae), trinucleate. Nectar glands receptacular, highly diversified in number, shape, size, and disposition around filament bases, always present opposite bases of lateral filaments, median glands present or absent. Pistil 1, 2-carpelled; ovary superior, sessile or borne on a distinct gynophore, 2-locular and with a false septum connecting 2 placentae, rarely unilocular and eseptate; placentation parietal, rarely apical; ovules 1–300 per ovary, anatropous or campylotropous, bitegmic, crassinucellate or rarely tenuinucellate; megagametophyte (embryo sac) of the Polygonum type. Fruits typically a 2-valved capsule, arbitrarily termed silique (siliqua) when length at least 3´ width, or silicle (silicula) when length less than 3´ width, dehiscent or indehiscent, sometimes nutletlike, lomentaceous (Chorispora), samaroid (Isatis), or schizocarpic and [with] or without a carpophore carrying the 1-seeded mericarp (Cremolobus, Heliophila, Menonvillea), segmented or not, terete, angled, latiseptate (flattened parallel to septum), or angustiseptate (flattened at a right angle to septum); gynophore absent or sometimes distinct, sometimes 1–2.8 cm (Lunaria, Stanleya) or rarely to 10 cm (Aphragmus hinkuensis); valves 2, rarely or 3–6 (some Rorippa and Tropidocarpum), obscurely to prominently 1–7-veined, glabrous or pubescent, rarely spiny (Pugionium) or glochidiate (Asperuginoides, Clypeola), dehiscing acropetally or rarely basipetally, sometimes spirally or circinately coiled; replum (persistent placenta) rounded, rarely flattened or winged; septum complete, perforated, reduced to a rim, or lacking, sometimes with a midvein or few to many anastomosing veins; style 1, persistent, or rarely caduceus (Litwinowia), sometimes obsolete or absent; stigma capitate or conical, entire or 2-lobed, lobes spreading or connivent, sometimes decurrent, free or connate, opposite valves or repulum, rarely elongated into horns or spines (some Matthiola). Seeds usually yellow or brown, rarely black or white, flattened or plump, ovoid, oblong, globose, orbicular, or ovate, uniseriately or biseriately arranged in each locule, rarely aseriate, winged or wingless, mucilaginous or not when wetted; embryo oily, occupying the entire seed, strongly curved or very rarely straight and with a tiny radicle (Leavenworthia); cotyledons entire or emarginated, rarely bifid to base (some Schizopetalon), variously oriented in relation to radicle: incumbent (embryo notorrhizal: radicle lying along back of 1 cotyledon), accumbent (embryo pleurorrhizal: radicle applied to margins of both cotyledons), conduplicate (embryo orthoplocal: cotyledons folded longitudinally around radicle), spirally coiled (embryo spirolobal–Bunias), or twice transversely folded (embryo diplecolobal–Heliophila); endosperm absent; germination epigeal.

Type genus: Brassica Linnaeus.


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