Sirodot, non Bory
There are two species in the British Isles:-
- Lemanea fluviatilis (L.) C.Ag.
- Lemanea fucina Bory
Lemanea is a freshwater alga, a species in the Phylum Rhodophyta (Red Algae) of the Order Batrachospermales. Both species are considered to be widespread in the northern hemisphere. Although placed in the Rhodophyta (Red algae) it in fact is green in colour.
Lemanea is a stiff bristle-like branched or unbranched plant similar to a coarse horsehair. Close inspection show it to have small swellings at more or less regular intervals along its length. It grows to 10 cm in length, in bunches in freshwater. It is blue-green to olive in colour when young.
The genus is considered to be cosmopolitan in the northern hemisphere.
Irish records 
The records of this genus in Ireland are few with only three historic records from the north of Ireland in the Ulster Museum Herbarium (BEL). One collected by William Thompson in 1839; one collected by W. Sawers in 1856 and one collected in 1884 by H.W.Lett. These seem to be the earliest records from the north of Ireland. A more recent specimen collected in 1959 by Miss M.P.H. Kertland near Dungiven, Co. Londonderry is also preserved. A further 16 specimens collected recently, that is within the last 50 years, have been added to the collection - all from Northern Ireland. We have one foreign specimen collected recently from the Faroes. Recently Lemanea fucina has been reported from Clare Island.
- Lemanea borealis Atkinson
- Lemanea fluviatilis (Linnaeus) C.Agardh
- Lemanea fucinia var. parva M.L. Vis & R.G. Sheath
World-wide 10 species are listed in algaebase:- 
- Lemanea borealis' Atkinson
- Lemanea ciliata (Sirodot) De Toni
- Lemanea condensata Israelson
- Lemanea fluviatilis (Linnaeus) C. Agardh
- Lemanea fucina Bory de Saint-Vincent
- Lemanea fucina var. parva M.L.Vis & R.G. Sheath
- Lemanea mamillosa Kützing
- Lemanra rigida (Sirodot) De toni
- Laminea sinca C.C. Jac
- Lemanea sudeica Kützing
'A Lemanea species was found on slabs in the rapidly flowing streams in the NW of the Island' (Hibberd, D.J. in The Island of Mull a survey of its flora and environment. Ed A.C. Jermy and J.A. Crabbe. British Museum (Natural History) London. 1978).
- Guiry, M.D., John, D.M., Rindi, F. and McCarthy, T.K. (Edited) 2007. New Survey of Clare Island. Volume 6: The Freshwater and Terrestrial Algae. Royal Irish Academy. ISBN 978-1-904890-31-7
- Vis, M,L, and Sheath, R.G. 1992. Systematics of the freshwater red algael family Lemaneaceae in North America. Phycologia. 31: 164 - 179
General references 
- John, D.M., Whitton, B.A. and Brook, A.J. (Ed.) 2002. The Freshwater Algal Flora of the British Isles. Cambridge University Press.
- Morton, O. 1978. Lemanea in the north of Ireland. Ir. Nat. J. 19: 205.
- Sawers, W. 1854. List of algae gathered in the north of Ireland. Naturalist, Morris 4: 254 - 257.
- West, G.S. and Fritsch, F.E. 1927. A Treatise on the British Freshwater Algae. Cambridge University Press, Cambridge. [Facsimile edition printed in 1968 as Vol. 3 of Bibliotheca Phycologia. J.Cramer, Lehre.]
Further reading 
- Scannell, M.J.P. 1977. Localities in Cork East for Lemanea sp. (Rhodophycea) Ir. Nat. J. 19: 25.