Petroselinum (Apiaceae for Flora Nordica)

Hemicryptophyte (biennial). Heterophyllous, to 70(–80) cm; taproot 2–16 mm thick; both the root and the leaves with an aromatic scent. Stem solid, sometimes subsequently hollow; basal part 2–5.5 mm thick, terete to angular (rarely sulcate), pale green, slightly glaucous; upper internodes sulcate. Leaves 2–7 at the base (usually withered before anthesis) and 7–15 on the stem, one of the basal leaves is the largest; sheath narrow, not purplish, on the upper leaves with a whitish border having rounded tips; petiole 4–9.5(–15) cm; blade 2-pinnate, 3–7.5(–9) × 3–5(–11) cm (length/width ratio 0.8–1.9). Primary leaflets 2–3(–4) pairs; angle leaflet/rachis 30–55°; longest petiolules 0.7–1.8(–2.4) cm. Ultimate leaflets 2–5-pinnatifid, with 3–5 pairs of lobes/teeth (the uppermost lateral ones often reaching above the apical one); petiolule 5–19(–35) mm; blade 11–30 × 14–29(–55) mm (length/width ratio (0.55–)0.7–1.1); base narrowly cordate to shortly attenuate. Ultimate lobes 1.5–5.5 × 1.7–4.3 mm, with a length/width ratio of 0.6–1.5(–2.1) (in upper leaves narrower and more elongated, 11–25 × 1–1.6 mm, with a length/width ratio of 7–25); apices acute to cuspidate (usually acuminate), hyaline.

Umbels usually slightly convex, 2–3.5 cm high and 3.5–6.5 cm wide; peduncle 2–9 cm; rays straight, 1.5–4 cm, glabrous. Bracts 0(–7), persistent, 4–11 × 0.5–1 mm, membrane-bordered. Umbellules (5–)10–19; pedicels 0.3–0.8 cm, glabrous. Bractlets 4–9, persistent, 2.5–4.5 × 0.3–0.9 mm, membrane-bordered. Flowers not to slightly zygomorphic, (10–)15–28 per umbellule; sepals 0.1–0.5 mm; petals yellow to light yellow, 0.6–1.1 × 0.6–1 mm, emarginate (apical cut 0.1–0.2 mm deep); filaments 1.3–2.1 mm; anthers 0.4–0.6 mm. Fruit slightly laterally flattened, broadly ovate in outline; carpophore slightly flattened, divided. Mericarps 1.9–2.7 × 0.8–1.2 × 0.9–1.3 mm (length/width ratio 2.1–2.8), with pale, low and rather narrow ridges; valleculae wide, with dark-brown vittae; stylopodium conical, 0.3–0.5 mm wide; style 0.5–0.9 mm, directed outwards or deflexed. – Mid-summer to late summer.

Distribution and habitat. – Frequently grown in gardens and as a cash crop, and occasionally found as a relic, a throwout or an escape; probably also brought in with transports. Abandoned crofts, earth heaps, dumps, streets, docks; rarely naturalized on seashores. – Reported as resident at least from D Sjæ Stevns (since 1933, coastal slope), Brn Christiansø (rocky islet, since 1948), S Öl Böda (frequent on seashore, known since 1964), Gtl Visby 1908–17 (Johansson 1917) and Gotska Sandön (Ingmansson & Petersson 1989). Elsewhere probably casual (clearly under-recorded): D scattered (rare in parts of VJy). N recorded from the southeast and along the coast to VA; ST Trondheim 1926. S scattered records mainly from the southern part. F recorded as an escape from dumps and roadsides at least in A, V, U and KP.

The Nordic material is usually heterophyllous with the lower leaves being more broad-lobed, but several specimens have only narrow-lobed leaves (e.g. from S Öl Böda). Also the shape of the margin varies (crispate or flat). There is a correlation between crispate leaves and some other characters (e.g., up to 5-pinnatifid ultimate leaflets with a narrowly cordate base and cuspidate apices) but they are probably only different expressions of the same character (i.e., leaflets with proportionally longer margins). Thus, the variation in leaf morphology may be dependent on a few genes only. However, also the size of the umbels seems to be correlated with the shape of the margins, morphotypes with crispate leaves having 3.5–4.5 cm wide umbels at fruiting stage, and morphotypes with flat leaves having 5–6.5 cm wide umbels.

One deviating specimen (S Stockholm) has few-lobed leaves with linear and entire, extremely elongated lobes (to 8 cm). Since such lobes occur intermingled with ordinary lobes on the same leaf in a few other specimens (from S BhG Göteborg, Vg Sala, Vrm Arvika, and Nrk Mosjö), the character has probably no taxonomic significance.

Similar taxa. Petroselinum crispum in flower is quite distinct from Aethusa cynapium which has umbels with deflexed bractlets, usually only three per umbellule, and flowers with white petals. However, non-flowering specimens of A. cynapium may be very similar to flat-leaved morphotypes of P. crispum, but can be recognized by the more narrow-lobed leaves with acute to acuminate apices, and – if fresh – by the absence of the typical scent of parsley. However, leaf shape is variable in both P. crispum and A. cynapium, and some herbarium specimens without developed umbels may not be possible to determine with certainty. – See also Apium graveolens.