Glabrous, glaucous, erect annual. Stems ± solid, grooved, striate, up to 150 cm high. Basal lvs (1)-2-pinnate, long-petiolate; ultimate segments narrowly elliptic or ovate, coarsely and irregularly serrate, sometimes lobed, 2-10 cm long, sessile or shortly petiolate; stem lvs reduced, (1)-2-3-pinnate, shortly petiolate, with lanceolate to linear or pinnatisect, acuminate segments. Umbels 2-11 cm diam.; rays numerous, fine and incurved at fruiting; bracts numerous, 3-fid or pinnate with filiform to lanceolate segments; bracteoles numerous, linear-lanceolate. Fls numerous, white, 2-3 mm diam. Fr. brown with pale ribs, c. 2 mm long; vittae prominent.