Parsley water-dropwort

Oenanthe lachenalii, the parsley water-dropwort, is a perennial herb in the family Apiaceae (Umbelliferae) native to western and central Europe, occurring in damp brackish coastal marshes, dune slacks, salt-meadows, and the upper edges of saltmarsh and estuarine grassland from Britain and Ireland south to Iberia and east to the Baltic. Like its relatives in the genus Oenanthe, it is highly toxic, containing the polyacetylene oenanthotoxin in all parts. The plant arises from a cluster of slender fusiform tuberous root-fibres and produces a slender erect grooved hollow stem 30-100 cm tall, branched in the upper portion. The basal and lower leaves are bipinnate to tripinnate with small narrow lanceolate segments, withering early in summer; the upper stem leaves are smaller, with narrowly linear leaflets. The inflorescence is a compound umbel 3-6 cm across, the 5-15 rays of unequal length, each topped by a partial umbel of small white flowers, the outer flowers with slightly enlarged outer petals. The involucre below the umbel consists of several narrow bracts, and there are similar bracteoles below each partial umbel. The fruit is a cylindrical to ovoid schizocarp 2-3 mm long with prominent ribs and a swollen persistent stylopodium, the styles short and erect.