Basal leaves long-petiolate (petiole ± 8–16 cm.), bi- or subtripinnate, deltoid in outline, the lower pinnules also stalked; leaflets ovate to elliptical, acuminate or acute, cuneate to subcordate at the base, regularly or irregularly jaggedly toothed with mucronate teeth, terminal leaflets largest, entire or trifid, ± 2–4 × 1–2.5 cm., rhachis and all leaflets ± multicellular-pilose at least on the primary venation of the lower surface; sheaths short and broad, oblong to triangular, striate; lower stem leaves similar but more shortly petiolate; median stem leaves more deeply toothed and with longer and narrower leaflets, the terminal longest, ± 3–8 × 0.7–2 cm., sheaths longer and narrower; uppermost leaves very deeply and narrowly divided.
Stem ± terete, hollow, pale-striate, glabrescent below the inflorescence to ± furnished throughout with brownish multicellular hairs.
Perennial herb, ± 0.5–2.5 cm., with an underground creeping rootstock, sparingly branched above.
Petals ± 1 mm., white, occasionally greenish or violet tinged.
Umbels numerous, on divergent subglabrous to multicellular-pilose, 2–8 cm. peduncles; rays (3–)4–6, distinctly multicellular-pilose (rarely subglabrescent when past fruiting), 1–3.5 cm.; involucre of 1–3 linear bracts ± 1 cm. long; flowers (4–)7–9 in each partial umbel, of which 2–3 are hermaphrodite and producing fruit on 3–12 mm. pedicels, the remainder ♂ on 2–4 mm. pedicels, all pedicels pilose; involucel of 1–3 linear bracts ± equalling the pedicels of the ♂ flowers.
Fruit ovate, 3–5 × 2.5–3 mm., laterally compressed, distinctly short-pilose when young but glabrescent at maturity, blackish when ripe with greenish ribs; calyx-teeth totally obsolete; stylopodia long-conical, shorter than the ± 1 mm., divergent or somewhat recurved styles.