Annuals; puberulent, (trichomes clavate). Stems simple or several from base, erect to decumbent, branched (several) distally, 0.5-2.4(-3.2) dm. Basal leaves (soon withered); not rosulate; petiole 0.8-2.5 cm; blade 1- or 2-pinnatifid, 3-5.6 cm, margins (of lobes) entire or dentate. Cauline leaves petiolate; blade pinnatifid (similar to basal), 0.7-2 cm × 2-10 mm, base attenuate to cuneate, not auriculate, margins dentate to incised or pinnately lobed. Racemes (paniculate), elongated, (often dense) in fruit; rachis puberulent, trichomes straight or curved, clavate. Fruiting pedicels ascending to divaricate, straight or slightly recurved, (terete), (1.4-)1.6-2.3(-2.9) × 0.1-0.15 mm, puberulent adaxially. Flowers: sepals (tardily deciduous), oblong, 0.5-0.7 × 0.3-0.4 mm; petals (absent or rudimentary), white, linear, 0.2-0.4 × 0.05 mm, claw absent; stamens 2, median; filaments 0.5-0.8 mm; anthers 0.1-0.15 mm. Fruits ovate-elliptic, 1.7-2.1 × 1.2-1.6 mm, apically winged, apical notch 0.1-0.2 mm deep; valves thin, smooth, not or weakly veined, glabrous; style 0.1-0.15 mm, included in or equaling apical notch. Seeds oblong, 0.8-1 × 0.5-0.6 mm.

Flowering May-Jul. Alluvial fans, sandy flats, rocky hillsides, grassy valleys, canyons; 1500-1900 m; Tex.; Mexico (Chihuahua, Durango, Federal District, Hidalgo, Sinaloa, Zacatecas).