Greater water parsnip Sium latifolium - FreshwaterLife

Conserving 

our wildlife 

Greater water parsnip Sium latifolium 

Identification, habitat management and distribution

We are the Environment Agency. It’s our job to look after 

your environment and make it a better place – for you, 

and for future generations. 

Your environment is the air you breathe, the water you 

drink and the ground you walk on. Working with business, 

Government and society as a whole, we are making your 

environment cleaner and healthier. 

The Environment Agency. Out there, making your 

environment a better place. 

Published by: 

Environment Agency 

Rio House 

Waterside Drive, Aztec West 

Almondsbury, Bristol BS32 4UD 

Tel: 0870 8506506 

Email: enquiries@environment-agency.gov.uk 

www.environment-agency.gov.uk 

© Environment Agency 

All rights reserved. This document may be reproduced 

with prior permission of the Environment Agency. 

March 2006

The greater water parsnip is a 

wetland flower, found in wet ditches, 

tall herb fens and marshes. It has 

declined rapidly in the last 40 years. 

We want to halt 

its decline before 

it is too late. 

The greater water parsnip is one of 

nearly 400 species identified in the 

UK Biodiversity Action Plan as needing 

our protection. We work to protect these 

species for the generations that come after us: 

your help could make all the difference. 

This leaflet shows you how to recognise the greater water 

parsnip, and describes the conditions in which it will 

thrive. Simple changes, such as limited grazing and gentler 

ditch clearance, may be all that is needed to allow this 

plant to flourish. 

Acting now and adapting your management practices, 

if necessary, will make a difference. If you find the greater 

water parsnip on your land, or in the area you work, 

please get in touch. Your feedback will allow us to target 

surveys and improve our knowledge of the current places 

where the greater water parsnip can be found. 

You can record possible sightings on our website 

at www.environment-agency.gov.uk/conservation. 

Please give a national grid reference if you can. 

seed head 

Environment Agency Conserving our wildlife – Greater water parsnip Sium latifolium 3

Identification 

Key points: 

• tall (up to 2m); 

• hairless, perennial plant 

with strongly ridged stems; 

• flowers: white, large umbels 

(50–100mm in diameter) from 

July to September; 

• aerial leaves are pinnate with 

about five pairs of toothed leaflets; 

• feather-like submerged leaves 

that are not always present; 

Howes 

G by 

• fruits: oval, with prominent ridges; 

sets seed in September or October; 

• poisonous if eaten. Illustrations 

Habitat 

The greater water parsnip is found 

in wet ditches and tall herb fens and 

marshes. The plant grows in shallow, 

still or slow-moving water and is generally 

found on peat or alluvial soils. 

Once established, the greater water 

parsnip can grow among other tall 

wetland plants such as common reed 

(Phragmites australis) or reed-mace 

(Typha spp). However, the habitat 

must be more open for its seeds to 

germinate and young plants to grow. 

4 Environment Agency Conserving our wildlife – Greater water parsnip Sium latifolium 

The greater water parsnip will not 

survive in heavy shade – for example 

in alder or willow carr wet woodlands. 

However, it can grow at the edge of 

reed beds and osier beds, provided 

it is protected from over-grazing. 

Long periods of heavy grazing, 

frequent cutting or extensive ditch 

clearance will all damage the greater 

water parsnip’s chances of survival.

Status 

In the UK, the greater water parsnip 

is classified as endangered having 

declined rapidly over the last 40 

years. The plant receives general 

protection under the Wildlife and 

Countryside Act 1981 (as amended). 

The greater water parsnip is listed as 

a UK Biodiversity Action Plan (BAP) 

species, and has national and local 

Biodiversity Action Plans. For more 

information, see the BAP website: 

www.ukbap.org.uk ditch habitat 

Distribution 

The greater water parsnip is 

found on lowland floodplains. 

It has strongholds in: 

• Eastern England, eg the Ouse 

Washes in Cambridgeshire 

and Norfolk; 

• Southern England, 

eg Romney Marsh in Kent; 

• Loch Erne in 

Northern Ireland. 

Habitat restoration and 

appropriate management 

are required in these and 

other historic locations. 

This will maintain and 

increase its distribution, 

ensuring the long-term survival 

of the species. 

Distribution of greater water parsnip 

Number of 

10km 2 occurrences 

1987–1999 

1970–1986 

Pre-1970 

Environment Agency Conserving our wildlife – Greater water parsnip Sium latifolium 5 

Map source: New Atlas of the British and Irish Flora

Management 

Sympathetic management is required to assist the plant’s 

continued survival. These management guidelines are 

based on the best knowledge currently available. 

• Clean ditches sensitively – rotate clearances; leave 

alternate lengths untouched; if you can, leave plant roots 

in place. 

• Cut back vegetation infrequently and leave some patches 

uncut. Cut after October when seed is set. 

• Prevent excessive shading from shrubs and trees. 

• Allow minimal cattle grazing – where grazing is 

beneficial for other species consider excluding cattle 

until after the greater water parsnip has set seed, 

and/or allow grazing only in certain years. Limited 

grazing helps the plant, by creating poached and 

more open areas in which seeds can germinate. 

• Maintain water levels at or near ground level all 

year round. The greater water parsnip is at risk 

from drying out in summer, and from the freezing 

of its roots in winter. The plant can tolerate high 

winter flooding and benefits from being submerged 

(50–100mm) in winter. 

• Create suitable habitats alongside existing populations 

– this will encourage the greater water parsnip to spread 

and increase in number. Grazing and trampling by cattle 

for one or two years will open up an adjacent patch of 

vegetation. Then, when young plants are established, 

exclude the livestock with ditches or fencing to create 

islands of taller vegetation. 

• Re-introduction may be an option, where natural 

regeneration from the seed bank is not possible. Only use 

seed collected from the same catchment following the 

guidelines from the Joint Nature Conservation Committee 

(JNCC). The Sium steering group can provide more 

information on seed propagation and re-introductions. 

6 Environment Agency Conserving our wildlife – Greater water parsnip Sium latifolium 

fen habitat

References: 

The Vascular Plant Red Data List for Great Britain, 

C M Cheffings and L Farrell (eds), JNCC, 2005 

A Policy for Conservation Translocations of Species 

in Britain, JNCC, 2003 

New Atlas of the British and Irish Flora, C D Preston, 

D A Pearman and T D Dines, Oxford University Press, 2002 

Acknowledgments: 

The Sium steering group brings together experts from 

the various organisations working to protect the greater 

water parsnip. The group would like to thank all those who 

helped to produce this leaflet. This leaflet has been jointly 

funded by the Environment Agency and English Nature. 

Further information 

The Environment Agency co-ordinates the national BAP 

for greater water parsnip and English Nature are the 

national BAP contact point. 

English Nature advises the government on wildlife issues. 

It is funded by Defra, the Department for Environment, 

Food and Rural Affairs. English Nature works to champion 

wildlife and to protect and enhance those species which 

currently face the threat of extinction. 

You can contact English Nature at: 

Northminster House 

Peterborough, PE1 1UA 

Telephone: 01733 455000 

Website: www.english-nature.org.uk 

In 2006 English Nature will become part of a new 

integrated government agency – Natural England. 

The new agency will also have parts of the Countryside 

Agency and the Rural Development Agency. 

Environment Agency Conserving our wildlife – Greater water parsnip Sium latifolium 7

Would you like to find out more about us, 

or about your environment? 

Then call us on 

08708 506 506 (Mon–Fri 8–6) 

email 

enquiries@environment-agency.gov.uk 

or visit our website 

www.environment-agency.gov.uk 

incident hotline 0800 80 70 60 (24hrs) 

floodline 0845 988 1188 

Environment first: This publication is printed on paper made 

from 100 per cent previously used waste. By-products from 

making the pulp and paper are used for composting and fertiliser, 

for making cement and for generating energy. 

GEHO0306BKJJ-E-E

Greater water parsnip Sium latifolium - FreshwaterLife

Create successful ePaper yourself

Delete template?

Save as template?