Iris pseudacorus

Tracheophyta MagnoliopsidaIridaceaeIrisIris pseudacorus


A rhizomatous perennial herb of wet meadows, wet woods, fens, the margins of lakes, ponds and watercourses, wet dune-slacks, and, in N. and W. Britain, also of coastal streams, shingle, upper saltmarshes and raised beaches. It reproduces by seed and by vegetative spread. Plants have occasionally been planted in the wild or have escaped from cultivation. Generally lowland, but reaching 480 m at Nenthead (Cumberland).



World Distribution

European Southern-temperate element; widely naturalised outside its native range.

© M. Cotterill, IWNHAS

Broad Habitats

Fen, marsh and swamp (not wooded)

Light (Ellenberg): 7

Moisture (Ellenberg): 9

Reaction (Ellenberg): 6

Nitrogen (Ellenberg): 6


Salt Tolerance (Ellenberg): 1

January Mean Temperature (Celsius): 3.7

July Mean Temperature (Celsius): 14.6

Annual Precipitation (mm): 1081

Life form information

Height (cm): 150

Perennation - primary


Life Form - primary

Non-bulbous geophyte (rhizome, corm or tuber)

Life Form - secondary

Perennial hydrophyte (perennial water plant)



Clonality - primary

Rhizome far-creeping

Distribution information

Count of 10km squares in Great Britain: 2563

Count of 10km squares in Ireland: 959

Count of 10km squares in the Channel Isles: 10

Atlas Change Index: 0.16

Weighted Changed Factor: 30

Weighted Change Factor Confidence (90%)


Distribution information

JNCC Designations


PLANTATT - Attributes of British and Irish plants. (.zip 1455KB) This dataset was compiled and published in 2004, and last updated in November 2008. Download includes an Excel spreadsheet of the attributes, and a PDF explaining the background and nomenclature. Note that the PDF version is the booklet as published, whereas the Excel spreadsheet incorporates subsequent corrections. A hardcopy can be purchased from the Centre for Ecology and Hydrology.

Atlas text references

Atlas (329c)
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.
Preston CD, Croft JM
1997.  Aquatic plants in Britain and Ireland.
Sutherland WJ
1990.  Biological Flora of the British Isles. No. 169. Iris pseudacorus L. Journal of Ecology. 78:833-848.