Greater water parsnip

Greater water parsnip

Greater water parsnip © Rachel Shaw

Greater water parsnip

Greater water parsnip © Rachel Shaw

Greater water parsnip

Scientific name: Sium latifolium
Large scale drainage in the UK has seen a massive reduction in the range of this sensitive aquatic plant which now only occurs in around 50 sites in England.

Species information


Height: Up to 2m

Conservation status

Classified as Nationally Scarce on the Vascular Plant Red Data List for Great Britain.
Protected in the UK under the Wildlife and Countryside Act, 1981.

When to see

Flowers July-September


Greater water parsnip is a large perennial with hollow stems and small white flowers. It is found in wetland areas. Unfortunately greater water parsnip has declined rapidly over the last 200 years due to the drainage of wetlands and loss of habitat.

How to identify

Identification can be confusing, as the plant is heterophyllous (has leaves of different shapes during development). Young aquatic leaves are submerged and finely divided while mature aerial leaves have serrated leaflets. This species is likely to be confused with lesser water parsnip which is abundant in many ditches. Greater water parsnip flowers through July to September with large, white, compound umbels.


Found in around 50 sites in the UK including Woodwalton Fen. More widespread in Ireland but still scarce.

Did you know?

The greater water parsnip is related to the humble carrot but unlike our beloved vegetable it is highly toxic.