Lathyrus palustris

Tracheophyta MagnoliopsidaFabaceaeLathyrusLathyrus palustris


A perennial herb of base-rich fens, reed-beds and fen-meadows; also, rarely, on marshy ground by rivers. Lowland.



World Distribution

Circumpolar Boreo-temperate element.

© K.J. Walker, BSBI

Broad Habitats

Fen, marsh and swamp (not wooded)

Light (Ellenberg): 7

Moisture (Ellenberg): 9

Reaction (Ellenberg): 7

Nitrogen (Ellenberg): 4

Salt Tolerance (Ellenberg): 0

January Mean Temperature (Celsius): 3.9

July Mean Temperature (Celsius): 15.4

Annual Precipitation (mm): 823

Height (cm): 120

Perennation - primary


Life Form - primary


Comment on Life Form

MOH suspects that it is geophyte



Clonality - primary

Rhizome far-creeping

Comment on Clonality

Extent of underground spread needs checking

Count of 10km squares in Great Britain: 57

Count of 10km squares in Ireland: 36

Count of 10km squares in the Channel Isles: 0

Atlas Change Index: 0.23

JNCC Designations


Scarce Atlas Account

Scarce Atlas Account: 

Lathyrus palustris L.

Marsh pea

Status: scarce



L. palustris is a perennial that climbs and scrambles over coarse vegetation. Its preferred habitats are base-rich and wet with tall grass, reed or scrub cover. In particular it is characteristic of rich fens in Britain, although on the continent of Europe it is more typical of habitats such as wet coarse grasslands and hay meadows on peat. It prefers well-lit sites on base-rich soils which are deficient in nitrogen. Characteristic associates include Calamagrostis canescens, Cladium mariscus, Eupatorium cannabinum, Juncus subnodulosus, Lysimachia vulgaris, Lythrum salicaria, Mentha aquatica and Phragmites australis. Peucedanum palustre and Thelypteris palustris grow with L. palustris at several of its eastern localities. This species is confined to the lowlands of Britain.

L. palustris spreads by seeds, but is a long-lived perennial.

L. palustris is declining in the eastern half of its British range, even within its strongholds in Broadland. It has declined in Fenland due to drainage and site destruction, whilst in wet hay-meadows, grassland improvement and reseeding have eliminated or modified the habitat. In Wales, however, several sites have been discovered since 1970, and the species was also discovered in Kintyre in 1976.

L. palustris has a very wide world distribution, being found throughout Europe, temperate and arctic Russia east to the Pacific, and temperate North America. It is rare in the Mediterranean region. 

The American var. pilosus (Cham.) Ledeb. persists at one site in a seasonally flooded dune slack at Tywyn Burrows (Vaughan 1978). It has been suggested that this population has its origins as a drift seed, having floated across from America on the North Atlantic Drift.



J. O. Mountford

Atlas text references

Atlas (117d)
Curtis TGF, McGough HN
1988.  The Irish Red Data Book. 1. Vascular Plants.
Hultén E, Fries M
1986.  Atlas of north European vascular plants north of the Tropic of Cancer. 3 vols.
Meusel H, Jäger E, Weinert E
1965.  Vergleichende Chorologie der zentraleuropäischen Flora. Volume 1. 2 vols.
Stewart A, Pearman DA, Preston CD
1994.  Scarce plants in Britain.