Stem simple or sparingly branched, terete, sometimes red-spotted, finely striate, the internodes long, upper branches sometimes opposite or in a whorl of 3.
Glabrous herb, probably biennial to perennial, 0.2–1.3 m.; root slender or somewhat thickened below the surface of the soil.
Umbels numerous, on mostly 1.5–9 cm. peduncles, rarely lateral and sessile on a branch; rays 4–11, glabrous, 1–4 cm.; involucre absent or of 1–4 small, linear bracts; flowers (3–)6–13 in each partial umbel, on glabrous, (3–)6–13 mm. pedicels; involucel of 1–3 small linear bracts, frequently unilateral.
Lower leaves 1–2-pinnate with 1–4 pairs of pinnae, when bipinnate these with 1–2 pairs of pinnules; very variable in form, with leaflets varying from ovate with jagged, acute teeth with anastomosing veins and up to ± 2 × 1 cm. to narrowly linear and remotely sharply toothed, 20–160 × 2–5 mm. with parallel veins; veins always prominent on the lower surface; petiole 2.5–20 cm.; sheath tapering into the petiole, 1–4 cm., strongly nerved, membranous-margined; upper leaves rapidly reducing, sessile on the sheaths, narrowly divided with entire or toothed segments, the uppermost very narrowly trisect.
Fruit elliptic-oblong to oblong-obovate, 4–5 × 2–2.5 mm., rather fleshy until quite mature, dorsally compressed, with a thick, pale margin, dark centrally, calyx obsolete; stylopodia rounded, purplish; styles of hermaphrodite flowers slender, ± 1 mm., ± deflexed, subequalling to slightly exceeding the stylopodia.
Petals ± 1 mm., blackish purple.