Plants 40–100 cm tall, hispid. Root cylindrical. Stem solitary, branched above. Basal leaves 2–3-pinnate; petiole, sheaths broad-ovate; blade lacerate-pinnatifid; ultimate segments lanceolate, 3–8 × 1–3 cm, base cuneate, margins coarsely serrate; terminal leaflets decursive at base. Cauline leaves gradually reduced upward. Terminal umbels 10–20 cm wide; bracts 2–3, linear; rays 25–35, unequal, 4–10 cm; bracteoles 5–8, linear, nearly as long as pedicels; umbellule 30–40-flowered. Calyx teeth lanceolate. Petals white, outer flowers in umbel radiant, enlarged petals deeply 2-lobed. Fruit obovoid, 6–7 × 4–5 mm, sparsely pilose; vittae solitary in each furrow, 2 on commissure, clavate, about 1/2 as long as mericarp. Seed face plane. Fl. Jul–Aug, fr. Sep. 2n = 22*.
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