- Name also: Keck (compare Cow Parsley), Common Hogweed, Eltrot (USA)
- Family: Carrot Family – Apiaceae (Umbelliferae)
- Growing form: Biennial or perennial herb.
- Height: 50–150 cm (20–60 in.). Stem roughly haired, 5–20 mm (0.2–0.8 in.) thick, hollow, joints with septa.
- Flower: Corolla regular (outer corollas sometimes slightly zygomorphic and larger than others), white–pale lime green, usually approx. 5 mm (0.2 in.) (sometimes up to approx. 15 mm (0.6 in.)) wide; petals 5. Sepals small–vestigial. Stamens 5. Pistil of 2 fused carpels, styles 2. Inflorescence up to 20 cm (8 in.) wide compound umbel, secondary umbels 15–45. Primary umbel’s bracts quickly withering, secondary umbels’ bracteoles enduring.
- Leaves: Alternate, stalked, base sheath-like. Blade pinnate, leaflets 5(–9). Leaflets pinnate, tapered, with serrated margins, underside hairy.
- Fruit: Widely elliptic–roundish, back very flat, 2-sectioned, glabrous–hairy, sometimes hairy-scaled, quite shallowly ridged, wide-winged, 7–8 mm (0.28–0.32 in.) long schizocarp, oil ducts narrow, linear.
- Habitat: Yards, gardens, broad-leaved forests, forested fields, wasteland, harbours, meadow banks, roadsides, beside railways.
- Flowering time: June–August.
Cow parsnip is a perennial plant: Finland has no less than four types of cow parsnip which are divided into two subspecies and their variations. The type species ssp. sphondylium is more-or-less rare and has arrived in lawn seed, ballast soil and German soldiers’ provisions to settle in to southern Finnish urban environments. It can be recognized by its white corolla and by the outer corollas on the secondary umbels which are somewhat unsymmetrical (outer petals are larger than the rest). Ssp. sibiricum is probably native to broad-leaved forests in the Åland Islands but is an alien species that has arrived mainly from the east during times of war and peace and is now found widely on banks, dry meadows and waste land in southern and central Finland, and more rarely in the north. It can be recognized by its yellowish green and more-or-less regular corolla. Both subspecies are further divided into varieties, which differ from each other with respect to the hairiness of the fruit and ovaries.
Cow parsnip can take up to ten years to flower. Some of the plants flower only once in their lives, the best up to ten times. There can be quite a buzz around cow parsnip, with even hundreds of different insect species visiting its flowers. Its most important pollinators are mosquitoes, flies, hymenopterans, butterflies, thysanopterans and colourful beetles.
The scientific name of genus is a reference to the legendary strongman Heracles. This comes from the great size of the genus or perhaps its diverse medicinal properties. Cow parsnip’s roots, leaves and schizocarps have been used to lower blood pressure, promote digestion, treat epilepsy, rashes and period problems. The schizocarps are used to prepare an aphrodisiac –and in Siberia it is used to make moonshine. Botanists should leave the plant in peace, however, because its juice is poisonous. Even just touching the plant, especially in sunlight, can cause great irritation to the skin.