Annual herb 20 cm - 0.5 m tall Stem: upright, branched near the apex, sparsely hairy. Flowers: in branched clusters (raceme). Sepals four, 1 - 1.3 mm long, broadly oval, and firm. Petals four, yellow, 1 - 1.5 mm long, narrowly spatula-shaped. Stamens six. Fruit: a small pod, 4 mm long, 3 mm wide, diamond-shaped to elliptic, flattened, obscurely notched. Lower leaves: pinnately divided into linear segments, sparsely hairy. Upper leaves: alternate, clasping, stalkless, much shorter than lower leaves, heart-shaped, bases lobed, tips pointed, lobes long and usually overlapping, sparsely hairy.
Similar species: Lepidium perfoliatum and Lepidium campestre are the only Lepidium species with lobed, clasping leaves. Lepidium campestre differs by being densely hairy all over.
Flowering: late May to early June
Habitat and ecology: Introduced from Europe. A weed found in disturbed areas, especially along roads and railroads.
Occurence in the Chicago region: non-native
Etymology: Lepidium comes from the Greek word lepis, meaning scale, which refers to the shape of the fruit. Perfoliatum means "with the leaf surrounding the stem."
Erect, sparsely hairy annual 2-5 dm, branched above; basal and lower cauline lvs pinnately dissected into linear segments; upper cauline lvs broadly ovate to subrotund, entire, deeply cordate, the rounded auricles about as long as the rest of the blade and usually overlapping; sep firm, broadly oval, 1-1.3 mm; pet narrowly spatulate, yellow, 1-1.5 mm; stamens 6; fr rhombic-elliptic, 4 נ3 mm, obscurely retuse; style about as long as the notch; 2n=16. Native of Europe, well established as a weed in w. U.S., e. to Mich. and O. and occasionally elsewhere in our range. May, June.Erect, sparsely hairy annual 2-5 dm, branched above; basal and lower cauline lvs pinnately dissected into linear segments; upper cauline lvs broadly ovate to subrotund, entire, deeply cordate, the rounded auricles about as long as the rest of the blade and usually overlapping; sep firm, broadly oval, 1-1.3 mm; pet narrowly spatulate, yellow, 1-1.5 mm; stamens 6; fr rhombic-elliptic, 4 נ3 mm, obscurely retuse; style about as long as the notch; 2n=16. Native of Europe, well established as a weed in w. U.S., e. to Mich. and O. and occasionally elsewhere in our range. May, June.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.
General: Introduced annual (sometimes biennial), 10-60 cm tall; stems single from base, erect, branched above; taprooted. Leaves: Strongly dimorphic, glaucous, basal leaves bi- or tripinnatifid with linear segments, 3.5-14 cm long, the segments entire; lower cauline leaves as described above, gradually reduced and modified upwards, the upper cauline leaves appearing perfoliate, ovate to orbicular, 1.4-3 cm long, margins entire, the base cordate, deeply clasping. Flowers: Inflorescence of numerous racemes, many-flowered, congested in flower and elongating somewhat in fruit; fruiting pedicels nearly round in cross-section, 3.5-8.5 mm long; sepals 1.1-2 mm long; petals oblanceolate to orbicular from a narrow claw, 2-3.5 (4.5) mm long, greatly surpassing the sepals, white to cream; stamens 6; flowers April-September. Fruits: Silicle, broadly obovate or rhombic-ovate to sub- orbicular, flattened, 3.7-4.5 (5) mm long, 3-4.2 mm wide, the apex scarcely notched (about 0.2 mm deep); mature style small, 0.2-0.4 mm long, equaling or exserted slightly beyond the notch; seeds brownish Ecology: Disturbed habitats, roadsides, agricultural lands; 1100- 2100 m (3500-7000 ft); Apache, Coconino, Navajo, and Pima counties; widespread throughout the U.S. Notes: This species, though not typically of forest habitat, is well documented in the vicinity of the San Francisco Peaks, specifically around Flagstaff. Editor: Springer et al. 2008