Erect annual to 20(–50) cm high, often multistemmed. Leaves usually 1-pinnate, upper leaves much smaller than lower, lamina to 5 cm long; leaflets 3–5, ovate-cuneate, to 2.5 cm long, often deeply 3-lobed and lobes again divided; margins crenate to toothed; petiole longer than lamina. Umbels 1–4 cm diam., sessile or subsessile; rays 3–4, unequal, 1–3-(–6.5) cm long; umbellules 3–10(–20)-flowered; pedicels to 5 mm long. Petals c. 0.5 mm long, white, often with reddish midrib. Fruit broad-ovoid, c. 1.5 mm long; mericarps with 5 slender pale ribs. Flowers Oct.–Feb.