Erect biennial, with a nauseous odour when crushed. Stems solid, striate, up to 120 cm high. Basal lvs 1-pinnate, sometimes lowest leaflets again divided, petiolate; leaflets in 3-8 pairs, ovate-elliptic, lobed and serrate, c. 2-7 cm long, usually subsessile; stem lvs reduced, usually 1-2-ternate, with segments linear or narrow-ovate and lobed or serrate. Umbels 1-5 cm diam.; rays (1)-2-5-(6), slender and somewhat irregular giving a diffuse appearance to the infl.; bracts 2-3, linear to subulate; bracteoles 1-4, usually subulate, rarely linear. Fls 2-5, white or greenish white, 1-2 mm diam. Fr. broadly ovate, 2-3 mm long, dark brown with lighter ribs.