Cicuta virosa aka Cowbane

Cicuta virosa is a perennial in the carrot family, Apiaceae. Common names include cowbane, water hemlock, and beaver poison. Its native range spans the subarctic and temperate Northern Hemisphere. The RHS records it as native to Britain and Ireland. It grows in wet places, including marshes and ditches. It also lives in shallow water over muddy ground. These habitats place it among plants of wetland edges.

The plant grows to about 4 feet [1.2 metres] tall. Its perennial habit means it survives for more than one year. Kew also classes it as a helophyte, a wetland growth form. Flowers appear from July to August, according to Plants For A Future. Each flower has both male and female organs. Bees and flies pollinate the flowers, and the species is self-fertile. The supplied records give no further flower or fruit details.

It grows in full sun or light shade. Plants For A Future lists sandy, loamy, and clay soils as suitable. It accepts mildly acid, neutral, and mildly alkaline soil. The same source notes a preference for acid ground. Soil should stay moist or wet rather than dry out. A bog garden matches these needs, but its poison risk matters. The evidence gives no hardiness zone or mature width.

Plants For A Future describes seed sowing in spring or autumn. Seeds can start in a cold frame before summer planting. It also mentions sowing seed straight into the ground. That source does not flag the plant as a weed. Its flowers provide a feeding site for visiting pollinating insects. No other practical uses appear in the supplied records. They give no details of pests or diseases.

This plant is highly poisonous and is not a food crop. Plants For A Future warns that even a small bite may kill. Its toxin, cicutoxin, harms the central nervous system. Poisoning can stop breathing through paralysis. One report records people eating boiled leaves, but the source rejects this as unsafe. Do not treat boiling as a way to make it edible. Past uses included root preparations and a homeopathic remedy. These records do not establish safe or effective treatment. The source states that herbal medicine does not use this highly toxic plant.