©Peter L Herring


Scientific name: Conium maculatum
A notoriously poisonous plant, hemlock produces umbrella-like clusters of white flowers in summer. It can be found in damp places, such as ditches, riverbanks and waste ground.

Species information


Height: up to 2m

Conservation status


When to see

June to July


A poisonous plant, hemlock has a repellent smell when its leaves are crushed, helping to ensure that accidental poisonings don't occur very often - even livestock studiously avoid it. This biennial plant prefers damp places and can grow in huge colonies on waste ground, riverbanks and ditches, but can also be seen along roadside verges. It produces umbels (umbrella-like clusters) of white flowers in June and July.

How to identify

A tall, upright plant, hemlock can be distinguished by the distinctive and unpleasant, mousy smell of its foliage and its purple-spotted stems. Its leaves are finely divided and large, and its flowers are small and white and appear in umbrella-like clusters.


Found in England and Wales, scarcer in Scotland and Northern Ireland.

Did you know?

The poisonous nature of hemlock features heavily in history - it was the plant that was given to the famous Greek philosopher, Socrates, at his execution. The toxins in hemlock are alkaloids, including coniine and gamma-coniceine, which cause muscular paralysis, leading to respiratory failure and eventually death. Only a tiny amount of Hemlock can prove fatal to a human or to livestock.

How people can help

Although they might not look especially wildlife-friendly, our roadside verges, railway cuttings and waste grounds can provide valuable habitats for all kinds of plants and animals.