Lepidium didymum L.
Family: Brassicaceae
(english: lesser swinecress)
[Carara didyma (L.) Britt.,  more]
Lepidium didymum image
Malcolm Storey  
Annuals; (fetid); glabrous or pilose. Stems few to several from base, erect to ascending or decumbent, branched distally, 1-4.5(-7) dm. Basal leaves (soon withered); not rosulate; petiole 0.5-4(-6) cm; blade 1- or 2-pinnatisect, 1-6(-8) cm, margins (of lobes) entire or dentate (sometimes deeply lobed). Cauline leaves shortly petiolate to subsessile; blade similar to basal, smaller and less divided distally, lobes lanceolate to oblong or elliptic, 1.5-3.5(-4.5) cm × 5-12 mm, base not auriculate, margins (of lobes) entire, serrate, or incised. Racemes elongated in fruit; rachis glabrous or pubescent, trichomes straight, cylindrical. Fruiting pedicels divaricate to horizontal, straight slightly recurved, (terete), 1.4-2.5(-4) × 0.15-2 mm, glabrous or sparsely pubescent adaxially. Flowers: sepals (tardily deciduous), ovate, 0.5-0.7(-0.9) mm; petals white, elliptic to linear, 0.4-0.5 × ca. 0.1 mm, claw absent; stamens 2, median; filaments 0.3-0.6 mm; anthers 0.1-0.2 mm. Fruits schizocarpic, didymous, 1.3-1.7 × 2-2.5 mm, apically not winged, apical notch 0.2-0.4 mm deep; valves thick, rugose, strongly veined, glabrous; style absent or obsolete, included in apical notch. Seeds ovate, 1-1.2 × 0.7-0.8 mm. 2n = 32. Flowering Mar-Jul. Roadsides, waste areas, lawns, pastures, fields, gardens, disturbed areas; 0-1000 m; introduced; B.C., N.B., Nfld. and Labr. (Nfld.), N.S., Que.; Ala., Ariz., Ark., Calif., Conn., Fla., Ga., La., Maine, Md., Mass., Miss., Mo., N.J., N.Y., N.C., Ohio, Oreg., Pa., S.C., Tenn., Tex., Va., W.Va., Wis.; South America; introduced also in Mexico (Sinaloa), Central America (Honduras), Europe, Asia, s Africa, Australia.
Annual or biennial herb with a long taproot 10 - 40 cm tall Leaves: alternate, pinnately divided, short-stalked, 4 - 5 cm long, to 2 cm wide, oblong. Leaf segments opposite, linear-elliptic to linear-oblong, tips pointed, sometimes bearing a few teeth along the margins. There is a foul odor when the leaves are crushed. Flowers: in a loose, 1 - 4 cm long branched cluster (raceme), which is borne opposite a stem leaf. Sepals four, oval. Petals four, white to greenish, tiny, barely exceeding sepals. Stamens six, sometimes two. Fruit: a short, round pod, tightly clustered, occurring in pairs, 1.7 - 3 mm long, flattened, coarsely wrinkled, notched at top and bottom, without a wing. Stems: multiple from base, decumbent or ascending, rounded, branching from a central point, sometimes thinly hairy.

Similar species: No information at this time.

Flowering: late June to mid-August

Habitat and ecology: Introduced from Europe. Rare in the Chicago Region. This weed has been found growing in a flowerbed, a vacant lot, the edge of a lawn, and in a shaded nursery area.

Occurence in the Chicago region: non-native

Etymology: Coronopus comes from the Greek word korone, meaning crown, and pous, meaning foot, which refers to the cleft leaves. Didymus means "in pairs."

Author: The Morton Arboretum

Foetid annual or biennial, thinly hairy, much-branched, spreading or ascending, 1-4 dm; lvs oblong, 1-3 cm (including the short petiole), pinnatifid, the segments entire or with a few deep teeth; racemes rather loose, 1-3 cm, the mature pedicels slender, 2 mm; fr didymous, distended over the seeds, coarsely wrinkled on the surface, 1.7-3 mm, cordate at base, evidently notched at summit, the style and stigma included in the notch; 2n=32. Native of S. Amer., established as a weed throughout our range and elsewhere, especially southward. Summer. (Carara d.)

Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.

©The New York Botanical Garden. All rights reserved. Used by permission.
Lepidium didymum image
© 2011 Barry Breckling  
Lepidium didymum image
Malcolm Storey  
Lepidium didymum image
© Forest & Kim Starr  
Lepidium didymum image
Sue Carnahan  
Lepidium didymum image
Sue Carnahan  
Lepidium didymum image
Sue Carnahan  
Lepidium didymum image
Lepidium didymum image
Lepidium didymum image
Lepidium didymum image
Lepidium didymum image
Lepidium didymum image
Lepidium didymum image
Lepidium didymum image
Lepidium didymum image
Lepidium didymum image
Lepidium didymum image
Lepidium didymum image
Lepidium didymum image
Lepidium didymum image
Lepidium didymum image
Lepidium didymum image
Lepidium didymum image
Lepidium didymum image
Lepidium didymum image
Lepidium didymum image
Lepidium didymum image
Lepidium didymum image
Lepidium didymum image
Lepidium didymum image
Lepidium didymum image
Lepidium didymum image
Lepidium didymum image
Lepidium didymum image
Lepidium didymum image
Lepidium didymum image
Lepidium didymum image
Lepidium didymum image
Lepidium didymum image
Lepidium didymum image
Lepidium didymum image
Lepidium didymum image
Lepidium didymum image
Lepidium didymum image
Lepidium didymum image
Lepidium didymum image
Lepidium didymum image
Lepidium didymum image
Lepidium didymum image
Lepidium didymum image
Lepidium didymum image
Lepidium didymum image
Lepidium didymum image
Lepidium didymum image
Lepidium didymum image
Lepidium didymum image
Lepidium didymum image
Lepidium didymum image
Lepidium didymum image
Lepidium didymum image
Lepidium didymum image
Lepidium didymum image
Lepidium didymum image
Lepidium didymum image
Lepidium didymum image
Lepidium didymum image
Lepidium didymum image
Lepidium didymum image
Lepidium didymum image
Lepidium didymum image
Lepidium didymum image
Lepidium didymum image
Lepidium didymum image
Lepidium didymum image
Lepidium didymum image
Lepidium didymum image
Lepidium didymum image
Lepidium didymum image
Lepidium didymum image
Lepidium didymum image
Lepidium didymum image
Lepidium didymum image
Lepidium didymum image
Lepidium didymum image
Lepidium didymum image
Lepidium didymum image
Lepidium didymum image
Lepidium didymum image
Lepidium didymum image
Lepidium didymum image
Lepidium didymum image
Lepidium didymum image
Lepidium didymum image
Lepidium didymum image
Lepidium didymum image
Lepidium didymum image
Lepidium didymum image
Lepidium didymum image
Lepidium didymum image