Plants 80–200(–300) cm, essentially glabrous. Basal leaves on long-petioles, petioles 7–25 cm, sheaths small, narrow; blades 2–3-pinnate, 10–30 × 6–28 cm, finely divided; pinnae petiolulate; ultimate segments oblong or ovate-lanceolate, 1–3 × 0.5–1 cm, short-petiolulate, incised or pinnatifid. Leaves gradually reduced upwards. Umbels 4–7 cm across, lateral umbels overtopping the terminal; peduncles 2–7 cm; bracts 4–6, ovate-lanceolate, acuminate, 2–5 mm, reflexed; rays 10–20, 1.5–4 cm, unequal; bracteoles 5–6, ovate, 1.5–3 mm, fused at base; pedicels 10–20, 1–5 mm, unequal. Petals ca. 1.5 × 1 mm. Fruit 2–4 × 1.5–2.5 mm. Fl. and fr. May–Aug. n = 11.

This notorious plant (hemlock) was famously used to kill Socrates. All part of the plants are poisonous (containing toxic alkaloids, C₈H₁₇N), but can be used medicinally to relieve pain and reputedly as a cancer cure.

Forest margins, cultivated field margins. Xinjiang [native to the Mediterranean region, widely naturalized in the N temperate zone].