Isoetes histrix

Tracheophyta LycopodiopsidaIsoetaceaeIsoetesIsoetes histrix


A small, summer-deciduous perennial, growing from a `corm`. It prefers skeletal acidic soils that are moist or flooded in winter but experience summer drought. A poor competitor, it is most frequent on pans of bare soil over S.-facing rock outcrops, but also grows on erosion pans and footpaths. It sometimes occurs in short turf, and in dune-slacks in Guernsey. Lowland.



World Distribution

Mediterranean-Atlantic element.

© Shannon, P

Broad Habitats

Inland rock (quarries, cliffs, screes)

Light (Ellenberg): 8

Moisture (Ellenberg): 7

Reaction (Ellenberg): 5

Nitrogen (Ellenberg): 1

Salt Tolerance (Ellenberg): 0

January Mean Temperature (Celsius): 6.6

July Mean Temperature (Celsius): 16.2

Annual Precipitation (mm): 829

Height (cm): 4

Perennation - primary


Life Form - primary




Clonality - primary

Little or no vegetative spread

Count of 10km squares in Great Britain: 3

Count of 10km squares in Ireland: 0

Count of 10km squares in the Channel Isles: 5

JNCC Designations


Atlas text references

Atlas (2d)
de Bolòs O, Vigo J
1984.  Flora dels Països Catalans, I. Introducció. Licopodiàcies-Capparàcies.
Jalas & Suominen (1972)
Bangerter EB, Cannon JFM, Jermy AC
1978.  Ferns and their allies. The Island of Mull: a survey of its flora and environment. :12.1-12.7.
Page CN
1997.  The ferns of Britain and Ireland, edn 2.
Wigginton MJ
1999.  British Red Data Books. 1. Vascular plants, edn 3.