Hemicryptophyte (perennial). To 100(--150) cm; rhizome creeping, to 9 mm thick, bearing lateral buds. Stem unbranched or branched only in upper part, hollow; basal part 3.5–5.5 mm thick, distinctly to indistinctly sulcate or rarely terete, sometimes red-violet, not or slightly glaucous, glabrous; upper internodes distinctly sulcate, not to distinctly papillose. Leaves 2–4 at the base and 3–7 on the stem; the innermost basal one usually the largest; sheath wide, sometimes red-violet, with rounded tips; petiole 7–31(–50) cm; blade unequally (1-)2-pinnate, 7–21 × 8–25 cm, with a length/width ratio of 0.8–0.9(–1.2), lower side slightly to distinctly glaucous, glabrous to densely hairy, upper side often with ± papillose veins. Primary leaflets 1–3 (usually 2) pairs; angle leaflet/rachis 45–60°; petiolules 0.8–4 cm. Apical leaflet entire or rarely with one pair of lobes; petiolule 0.9–2.4(–4) cm; blade ovate to narrowly ovate (rarely almost orbicular), 3.8–11.5(–17.5) × 2–7.5 cm (length/width ratio 1.2–2.7); margin doubly serrate, with white to slightly red-violet tips; base cordate to broadly cuneate; apex acute to acuminate (or rarely obtuse).

Distribution. Nem–SBor(–NBor). – Possibly indigenous in D, S and F according to studies made in southern and southeastern F (Suominen & Hämet-Ahti 1993), coastal S Upl (Almquist 1929), southern and southeastern S (e.g. Sterner 1938, Olsson & Tyler 2007) and beech forests in D (Egholm 1951). Also an early, perhaps medieval, incomer in several southern lowland areas (cultivated as a medicinal plant and vegetable); elsewhere brought in later, probably in the early 18th century, in northern parts not until the19th or 20th century. Strongly increasing throughout Norden during the 20th century, mainly spread with garden plants and soil. – D common; less common in western Jylland. N naturalized around Oslofjorden, elsewhere in man-made habitats; common in the lowlands and the valleys north to southwestern MR; further north rare to Fi Hammerfest. S common north to central Vrm, southern Dlr, and near the coast and in the valleys of the northern coastal provinces; fairly rare in northern Vrm, central and northern Dlr, easternmost Jmt and western Ång; rare and mainly casual in the inland from Hrj northwards (but established at least in eastern ÅsL). F common north to southern EP, southern PH, southern PS and PK, regarded as partly native (especially in the most fertile inlands) in herb-rich forests; much rarer and restricted to man-made habitats in the north. Fa rare but present on most of the larger islands. I rare as garden weed in a few towns and farms in coastal parts of IVe, INo and IAu.

Habitat. Preferably on moderately damp, nutrient-rich, mull-rich soil in shaded to rather shaded sites. The species is strongly favoured by fertilization and overgrowth. Thoroughly naturalized (or even indigenous, see Distribution), e.g. in deciduous woodland, along rivers and creeks in parts of the area, but much more common in habitats strongly influenced by man, viz gardens, parks, roadsides, railways, ditches and ruderal places, and over vast areas only seen in such places.

Biology. All flowers bisexual, but in peripheral flowers of primary and secondary umbels the stamens may be caducous. Extensively standforming, mainly by the strong rhizome; seedlings appear to be fairly rare. Germination rates of c. 30–60 % have been found in experiments (J. Nilsson pers. comm.).

Variation. In D NJy, Sjæ, S Sk and southern to western F, a morphotype with once pinnate leaves occurs, where leaflets are oblong to almost orbicular, with an obtuse apex.

Similar taxa. Aegopodium podagraria and Peucedanum ostruthium are similar when not in flower; for differences see the latter. See also Angelica sylvestris and Chaerophyllum aromaticum.