Glabrous annual herb 10-20 cm high with a single stem branching distally or from near the base; leaves basal and cauline, alternate, twice- or thrice-ternately compound, ultimate divisions filiform, broadly ovate in outline, basal leaves usually withered by flowering; umbels terminal and axillary, pedunculate, compound, with 4-7 rays bearing umbellets of 3-6 flowers; involucral bracts absent, involucel bractlets 1-4, linear, 1-3 mm long; flowers perfect, minute, with white petals; schizocarps broadly ovoid, 1.2-1.5 mm long, with three somewhat indistinct, rounded dorsal ribs, lateral ribs similar to the dorsal, surface with irregular corky banding perpendicular to the ribs and a few scattered multicellular tubercles on the ribs, tubercles sometimes with a straight, hair-like point. Flowering late March to early May.