- Name also: Poison Hemlock
- Family: Carrot Family – Apiaceae (Umbelliferae)
- Growing form: Biennial herb.
- Height: 50–150 cm (20–60 in.). Stem branched, glabrous, glossy, shiny, bluish grey, lower part with reddish brown spots, hollow, joints with septa. With repulsive fragrance.
- Flower: Corolla regular (actinomorphic), white, max. 5 mm (0.2 in.) wide; petals 5, notched, tip recurved. Sepals absent. Stamens 5. Pistil of 2 fused carpels, styles 2. Inflorescence a compound umbel, secondary umbels 10–20. Primary umbel usually with bracts, bracts narrowly lanceolate, descending oblique. Secondary umbels with 3–6 one-sided, basally united bracteoles.
- Leaves: Alternate, stalked, base sheath-like, stalk grooved, with membranous wings. Blade triangular, 2–3 times pinnate, dark green. Leaflets triangular–long, lobed–with serrated margins, lobe-tips white.
- Fruit: Egg-shaped–almost spherical, flat-sided, 2-sectioned, greenish brown, 2.5–3.5 mm (0.1–0.14 in.) long schizocarp. Thick-ridged with protuberances.
- Habitat: Yards, beside streets, wasteland, mills, fields, rubbish tips, loading areas, harbours.
- Flowering time: July–August.
Hemlock arrived in Finland with people a long time ago, which can be seen from the way that the species is still most prevalent in the south-west of the country around old inhabited areas. It likes nitrogenous soil, which could be found in the old days in fertilized yards and next to walls and later from harbours and farms. The seeds remain viable in the soil for a long time, even centuries, and the plant can appear surprisingly in places where it has not been known of for years. Hemlock also used to be cultivated beside walls on purpose because it was believed to absorb poisons that would otherwise be damaging to residents – although the plant itself was probably a bigger threat.
Hemlock is very poisonous. Its main poison is coniine, high levels of which are present in the stem and raw fruits especially when the plant is flowering and fruiting. The plant is not likely to be eaten, but even making a blow-pipe from its hollow stem has resulted in burning lips and nausea. Serious poisoning involves paralysis and begins with numbness in the feet and cold, which gradually spreads upwards throughout the body. In ancient Greece hemlock was dedicated to Hecate, the god of Hades who governed all the dark forces. Hemlock’s history is intertwined with death. Its most famous victim was the Greek philosopher Socrates, who was declared a heretic and forced to drink the poison. A hemlock poultice on the other hand was used in monasteries and armies to rein in sexual desire – its possible effect was probably due to its unpleasant smell of mouse urine.
Hemlock which is midway through its growing cycle is especially like cow parsley (Anthriscus sylvestris). In hot weather the plant stinks so badly that it cannot be confused with its relatives, but apart from the smell hemlock can be told apart from other members of the Carrot family with its bluish grey stem and mean-looking red spots on the bottom half. Its spherical fruit with their thick ridged protuberances also look totally different from cow parsley’s elliptic, glossy black fruits.