Slender, erect, annual herb, 2–7 dm tall, entirely glabrous; stems branching, with slender taproots. Leaves alternate and heteromorphic; basal leaves trifoliolate with flabelliform, incised leaflets 1–2.5 cm long; cauline leaves biternately decompound with linear-filiform ultimate divisions 3–10 mm long and 0.5–1.5 mm broad; petioles 1–6 cm long, sheathing. Inflorescence a loose, regularly compound umbel; rays 3–5, 1–2.5 cm long; involucral bracts usually absent; involucel bractlets 3–5, linear, 2–4 mm long. Flowers white, pinkish-white, or rose; sepals ovate-lanceolate, acute, often unequal, and conspicuous; petals oblong, conspicuously unequal with the outer radiant and possessing inflexed apices; stylopodium conic. Fruit orbicular and terete, 2–5 mm long, 1.5–3 mm broad, not constricted at the commissure, glabrous; ribs filiform to obscure; vittae obscure; carpophore 2-cleft to the base.