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."
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.