Hemicryptophyte (biennial). Glabrous, erect, distinctly aromatic plant, to 65 cm; tap­root vertical, 2–9 mm thick. Stem solid; basal part 2–7.5 mm thick, sulcate or sometimes angled, straw-coloured or slightly purplish, but not or indistinctly glaucous; upper internodes sulcate and usually winged. Leaves 3–6 at the base and 5–7 on the stem, the largest one is one of the basal or the lowest stem leaf; sheath narrow, not purplish, 1.8–2.5 cm, with an indistinct membranous border; petiole 5.5–20 cm; blade once pinnate, 3.5–7(–9) × 3–6(–7) cm, with a length/width ratio of 0.8–1.3(–1.6). Primary leaflets (1–)2(–3) pairs; angle leaflet/rachis 35–60°; longest petiolules 3–15 mm. Apical leaflet 2(–3)-pinnatifid, with 2–4 pairs of primary lobes; petiolule 3–17 mm; blade 11–26(–30) × 13–30(–34) mm, with a length/width ratio of 0.7–1(–1.2); margin not papillose, having cuspidate to acuminate teeth with white tips; base cuneate to truncate. Apical lobe 1.1–3.3(–4.5) × 2.4–6 mm (length/width ratio 0.3–0.8).

Distribution. Nem. – Indigenous on seashores in D (though by Egholm 1951 supposed to be a fairly late introduction) and perhaps also in southernmost S (though usually regarded as an escape, see Hylander 1971); elsewhere surely an escape from cultivation, and probably underrecorded. – D spontaneous in coastal areas in the southeastern part of the country east to LFM Møn (and possibly north to ØJy), but also cultivated and escaped around settlements; scattered in FyL, Sjæ and LFM, very rare in SJy (c. 5 localities, latest Als Sund 1976); further west and north only known as a rare casual (latest ØJy Søften 1975). S seashores along the southwestern coast, regarded as native but usually ± ephemeral (perhaps repeatedly spread from D): Sk few localities along Öresund, after 1960 only Skanör (at least 1981–2004), ± established also in Landskrona (records 1744, 1836–88), Malmö (1858–1916) and Vellinge (1822-31; Fries 1835), Hl Halmstad (wet meadow 1766, 1811; Georgson et al. 1997); also a casual escape: Sk c. 15 localities, Bl Mörrum and Rödeby 1990’s, Gtl Visby 1861, 1885, Klm Oskarshamn 1995, Torsås 1998, Västervik 1930’s, SmI Tingsås 1999–2001, BhG Göteborg 1898, 2000, Kungälv 1929. F reported as casual in U Helsinki 1949, EH Hattula 1990, PS Kuopio 1916, Kn Kajaani 1950 and OP Oulu 1988.– Records from S Bl Ronneby (Holmgren 1942) and S Mpd Skön (Collinder 1909) are due to confusion with Petroselinum crispum and Oenanthe aquatica. A record from S Hls (Å. Ågren 1996) should be verified.

Habitat. Moist to wet soil in full sun. Native occurrences mainly in seashore meadow, salt-marsh and with drift; cultivated forms occasionally escaped on various waste ground.

Similar taxa. Apium graveolens is similar to Petroselinum crispum, which has narrower leaf-lobes, umbels with long peduncles, several bractlets, yellow flowers, and longer anthers and styles (0.4–0.6 mm and 0.5–0.9 mm respectively). In Pastinaca sativa the stems are hollow, the umbels have long peduncles, the flowers are yellow, and the fruits are larger and winged.