Biennial or short-lived perennial.
Solitary herb with a thick tap root and a caudex 0.8—1.5 cm broad and covered with marcescent black leaf sheaths. Stems erect, up to 100 cm tall or more, up to 1 cm broad or more at base, with 15—20 ribs, sparsely hairy with very short (ca. 0.1 mm) stiff hairs making the stems rough, hairs denser and longer at the nodes. Stems hollow, compact at the distinct nodes, branched in their upper parts (inflorescence), green. Leaves basal (withering early) and cauline.
Leaves alternate. Basal leaves with petioles up to 20 cm; cauline leaves with short petioles extended into a clasping sheath on the stems. Blades triangular in outline, 15—20 × 15—20 cm, 3-pinnate with pinnatifid lobes, thin, green, glabrous except for short stiff hairs on the lower surface veins.
Inflorescences are compound umbels, usually several in the apical parts of the plant and from leaf axils. Main umbels 7—12 cm broad with 8—15 smooth rays without bracts. Partial umbels 2—3 cm broad with 10—15 smooth rays with 3—5 ovate bracts. Bracts green or purplish with white scarious and pubescent margins.
Flowers radially symmetric, epigynous (perianth attached at the top of the gynoecium), without sepals, with 5 petals ca. 4 × 2 mm, spathulate, usually with a notch at the apex, cream white. Stamens 5, filaments ca. 0.8 mm, anthers 0.1—0.2 mm. Gynoecium of 2 carpels with 2 short, divergent styles from a thickened or swollen basis (stylopodium).
Fruit dry, of two mericarps (part fruits) jointed at the top by the stylopodium with a central axis (carpophore). Mericarps 6—10 mm, narrowly oblong, with some very short, thick hairs at the base (apically on the pedicel), otherwise glabrous and smooth, blackish brown, glossy, with 2—3 ribs and a narrow beak. Each mericarp with one seed and spread separately.
Sexual reproduction by seeds; very local vegetative reproduction by fragmentation of rhizome. The flowers are adapted to pollination by insects, in Svalbard perhaps by flies. The plant was collected with flowers 25 Aug. 2008 and with immature fruits 26 Sept. 2011. However, the plant occurs as an extended population at its only known Svalbard locality, and since it is a comparatively short-lived plant, seed reproduction must take place quite regularly to upkeep this population.
Fruits are adapted to dispersal by large mammals.
As Anthriscus sylvestrisis is the only Apiaceae in Svalbard, and the only species there with 3-pinnate leaves and compound umbels, no mistake is possible.
Ruderal ground near cowshed and pigsty within a settlement.
Introduced. One large and stable population of Anthriscus sylvestris is known within the Russian mining town of Barentsburg (Nordenskiöld Land), obviously introduced with husbandry. See Alsos et al. (in press 2015). Otherwise, the species is European and W Siberian and common in agricultural areas north to beyond the arctic boundary in Norway and Russia.
Alsos, I.G., Ware, C. & Elven, R. In press 2015. Past Arctic aliens have passed away, current ones may stay. – Biological Invasions.