Erect, terrestrial perennial, with ovoid tubers towards ends of roots. Stems ± solid or hollow, striate, grooved, often purple tinged toward base, 30-90 cm high, not rooting at nodes. Basal lvs 2-pinnate, petiolate; ultimate segments ovate, lobed or not, serrate, 5-15-(20) mm long; stem lvs 1-2-pinnate with lanceolate to linear segments, or simple and entire. Umbels terminal, long-pedunculate, 2-6 cm diam.; rays 6-12; rays and pedicels much thickened at fruiting; bracts 0-10, linear; bracteoles numerous, linear. Fls numerous, white, 3-4 mm diam. Fr. cylindric, c. 3 mm long; ribs prominent, the lateral larger and spongy; styles somewhat thickened, > ⅔ length of fr.