- Name also: Marsh Hog’s Fennel, Hogfennel, Milk Parsley
- Family: Carrot Family – Apiaceae (Umbelliferae)
- Height: 50–100 cm (20–40 in.). Stem branched, bristly–grooved, glabrous, often purplish, hollow, joints with septa.
- Flower: Corolla regular (actinomorphic), white(–reddish), max. 5 mm (0.2 in.) wide; petals 5, shallowly notched, tip recurved. Sepals vestigial–absent. Stamens 5. Pistil of 2 fused carpels, styles 2. Inflorescence a compound umbel, secondary umbels 20–40. Primary and secondary umbels with pendant and linear bracts with membranous margins.
- Leaves: Alternate, stalked, leaf-base sheath-like. Blade triangular, 2–4 times pinnate. Leaflets pinnate, lobes narrowly linear, with entire margins and black tips.
- Fruit: Elliptic, flat-backed, 2-parted, thick-winged, wide-ridged, brown, 4–5 mm (0.16–0.2 in.) long schizocarp.
- Habitat: Shores, waterside meadows and thickets, swampy margins of ponds, wet swamps, fens, stream banks, ditches.
- Flowering time: July–August.
Milk-parsley is one of the most common umbellifers in Finland. Its carrot-like leaves appear on almost every shore in southern and central Finland but in the Oulu region it becomes quickly rarer and there are only a few plants growing in Lapland. Despite being so common, the species is exceptionally sparse: lone individuals can usually be found hiding among other shore-side vegetation. Milk-parsley is one of the best indicators for meadows that are periodically submerged under flood water. It thrives particularly in the boggy margins of small waterways and is rarer in hard-bottomed shores. It grows especially on sea-shores on the inner archipelago where the water is not so salty, and on the outer archipelago the higher salt levels force it to retreat to rocky ditches.
Milk-parsley is the main food of swallowtail butterfly caterpillars. Both the caterpillar and the adult butterfly warn off birds and other predators with their bright colours and bad taste, which is a product of compounds in the vegetation they eat which is stored in their bodies. Many poisonous insects do not actually produce poison but rather store poisonous substances from the food they eat. Milk-parsley was described in Carl von Linné’s texts as Finnish ginger (Finska Ingefähra), so ancient Finns probably used the aromatic, bitter-tasting plant as a medicine and even as culinary seasoning. Its root has also been chewed as a tobacco substitute.