Coronopus didymus (Linnaeus) Smith

Presently treated by Ihsan Al-Shehbaz as Lepidium didymum Linnaeus.

Herbs annual or rarely biennial, fetid, 10-45(-70) cm tall, glabrous or pilose with straight trichomes to 1 mm. Stems procumbent or erect, usually several from base, branched above. Basal leaves not rosulate, pinnatisect or bipinnatisect, 4-10 cm; lateral lobes 2-7(-10) on each side of rachis, variable in size, entire, dentate, or incised, acute. Middle cauline leaves similar to basal ones, 1.5-3.5(-4.5) × 0.5-1.2 cm, progressively smaller and less divided upward, shortly petiolate to subsessile; lobes lanceolate to oblong or elliptic, entire to serrate or incised. Racemes terminal or lateral and leaf opposed. Fruiting pedicels slender, ascending to divaricate or slightly reflexed, straight or recurved, 1.5-2.5(-4) mm, glabrous or pubescent. Sepals ovate, 0.5-0.7(-0.9) mm, ascending to spreading, glabrous or pubescent. Petals white, elliptic to linear, 0.4-0.5 mm. Stamens 2 or rarely 4, median; filaments white, dilated at base, 0.3-0.6 mm; anthers ovoid, 0.1-0.2 mm. Fruit 1.3-1.7 × 2-2.5 mm, didymous, compressed, emarginate at apex and base; valves subreniform, semicircular, or suboblong, prominently reticulate or rugose, rounded on back; style absent, sometimes obsolete, included in apical notch. Seeds oblong, curved, finely reticulate, 1-1.2 × 0.7-0.8 mm. Fl. Mar-Jun. 2n = 32.

Annual or biennial, 15-30 cm long, diffuse or procumbent, often somewhat foetid, branched mostly from below, glabrous or hairy. Basal and lower leaves rosulate, pinnatisect, stalked, 6-10 jugate, 5-10 cm long; upper leaves similar or pinnatifid and only 3-5-jugate, 1.5-3 cm long, sessile or subsessile; lobes sinuate toothed, often only on one side. Racemes 30-60-flowered, dense, up to 8 cm long (usually much shorter) in fruit. Flowers minute, c.l mm across; pedicel short, 3-4 mm long in fruit, filiform. Petals present or O. Stamens only 2 or 4, but only 2 fertile. Siliculae shorter than the pedicel, c. 1.5 mm long, 2.5 mm broad, broader than long, bilobed; valves globose, reticulately rugose, glabrous; septum very narrow, inconspicuous, c. 0.3 mm broad; seed c. 1.5 long, reniform, reddish-brown.

Anhui, Fujian, Guangdong, Hubei, Jiangsu, Jiangxi, Shandong, Sichuan, Taiwan, Xinjiang, Yunnan, Zhejiang [native to South America; naturalized elsewhere].

Distribution: Perhaps a native of S. America, but widely introduced almost throughout the world.

Fl.Per.: March June.

Roadsides, waste areas, fields; near sea level to 1000 m.

Lepidium didymum Linnaeus, Syst. Nat., ed. 12, 2: 433. 1767; Senebiera didyma (Linnaeus) Persoon; S. pinnatifida de Candolle.