Lower leaves very variable, broadly deltoid in outline, from simply pinnate to bipinnate with 1–2 pairs of pinnules in the lower pinnae, or even subtripinnate with small segments, the lower leaflets or pinnae shortly to longly (to as much as 10 cm. in larger bipinnate forms) petiolulate, upper sessile or subsessile; leaflets linear to narrowly or broadly lanceolate to broadly ovate, 2–25 × 0.6–6 cm., attenuate at each end to shortly cuneate or truncate at the base and acuminate above, subentire to denticulate or deeply irregularly, acutely or more bluntly serrate, with 2 distinct lateral veins parallel to the midrib in narrow-leaved forms, these indistinct by looping anastomoses in broader-leaved forms, veins smooth or commonly minutely roughened; petioles 0.7–2.2(–4) cm. including the shortly or more longly tapering, 1–3(–8) cm., striate sheath; median leaves ± similar but more shortly petiolate with smaller, narrower leaflets; upper leaves rapidly reducing, sessile on the sheaths, usually narrowly pinnatisect with more sharply toothed leaflets.
Umbels with 5–15 glabrous rays (5–)12–50 mm. long; involucre absent or of 2–4, filiform to lanceolate, 5–7 mm. usually early-withering bracts; partial umbels 5–18-flowered, pedicels slender, glabrous, 2–10 mm.; involucel of 4–8 linear, 1.5–4 mm. bracteoles; peduncles mostly 0.6–8 cm., the terminal umbels ± sessile with a male umbel arising immediately below.
Biennial (? sometimes perennial) herb, glabrous, 0.6–2 m. tall, foliage smelling of Angelica or Levisticum, the root of celery, with a slender to subtuberous rootstock.
Stem terete or slightly angular, striate, pale green to purple-spotted or eventually ± entirely reddish, 3–10 mm. wide at the base, considerably branched upwards with slender divergent branches.
Petals greenish yellow or cream, with an incurved tip, broadly elliptical or oblong to subrotund, ± 1 mm.
Fruit glabrous, round to elliptical or broadly obovate, shallowly notched at the base, deeply so and auriculate above with the auricles separated or contiguous, 4–12 × 4–8 mm. with the fertile centre 2–3.5 mm. wide, commissural vittae 4, the laterals in the wings; stylopodia conical, shorter than or subequalling the apical notch; styles filiform, 1.5–1.75 mm., purplish, divergent.