Erect terrestrial biennial, not rooting at nodes. Stems hollow, grooved, striate, up to 80-(100) cm high. Basal lvs 1-2-pinnate, petiolate; ultimate segments deltate or rhombic, lobed and crenate or dentate near apex, 2-4 cm long, ± sessile; stem lvs similar to basal but often apetiolate and becoming 1-pinnate or 3-foliolate with elliptic-obovate, entire or lobed segments. Umbels 2-5 cm diam., compound, ± sessile and lf-opposed, and so appearing bracteate; rays 4-15; bracts and bracteoles 0. Fls numerous, greenish white, c. 1 mm diam. Fr. broadly ovoid, dark brown, 1.5-2 mm long; ribs light brown, filiform.