Hydrilla verticillata

Tracheophyta MagnoliopsidaHydrocharitaceaeHydrillaHydrilla verticillata


In Britain and Ireland, H. verticillata grows in relatively deep water in mesotrophic lakes, only occasionally extending into the shallows. The Irish population is known to be female, but flowers have never been seen in Britain. Reproduction is by turions. Lowland.



World Distribution

Eurasian Southern-temperate element, with a continental distribution in W. Europe; widely naturalised outside its native range.

Broad Habitats

Standing water and canals

Light (Ellenberg): 6

Moisture (Ellenberg): 12

Reaction (Ellenberg): 9

Nitrogen (Ellenberg): 3

Salt Tolerance (Ellenberg): 0

January Mean Temperature (Celsius): 3.5

July Mean Temperature (Celsius): 14.2

Annual Precipitation (mm): 1555

Length: 100

Perennation - primary


Life Form - primary

Perennial hydrophyte (perennial water plant)



Clonality - primary

Detaching ramets above ground (often axillary)

Clonality - secondary

Detaching ramets at or below ground

Comment on Clonality

Bulbil like buds formed beneath substrate at tip of stolons; or turions in lf axils

Count of 10km squares in Great Britain: 2

Count of 10km squares in Ireland: 1

Count of 10km squares in the Channel Isles: 0

JNCC Designations


Atlas text references

Atlas (303a)
Curtis TGF, McGough HN
1988.  The Irish Red Data Book. 1. Vascular Plants.
Preston CD, Croft JM
1997.  Aquatic plants in Britain and Ireland.
Scannell MJP, Webb DA
1976.  The identity of the Renvyle Hydrilla. Irish Naturalists’ Journal. 18:327-331.