information on the biology of species and the ecology of habitats found around the coasts and seas of the British Isles

A red seaweed (Membranoptera alata)

Distribution data supplied by the Ocean Biogeographic Information System (OBIS). To interrogate UK data visit the NBN Atlas.
Only coastal and marine records shown



Membranoptera alata is a red or reddish-brown seaweed, up to 20 cm in length, with a flat, narrow frond. It exhibits a midrib and many fine, lateral veins, which can be clearly seen under a hand lens. It has many branches, arising from the central axis, which are irregular, dichotomous, and copiously branched in one plane. This perennial plant has a thin membranous thallus.

Recorded distribution in Britain and Ireland

Widely distributed throughout the British Isles but not recorded from parts of eastern England.

Global distribution

Common and widely distributed in north west Europe.


Grows on rocks or on other red and brown seaweeds as an epiphyte, particularly laminarians. Inhabits shady rock pools, the sublittoral and deeper waters.

Depth range


Identifying features

  • Blades width 0.6-2.4 mm.
  • Conspicuous midrib width of 0.15-0.5 mm, with many lateral veins.
  • Branches are irregular, dichotomous, and copiously branched in one plane.

Additional information

Membranoptera alata can sometimes be confused with Hypoglossum woodwardii. However, Hypoglossum woodwardii lacks the distinct lateral veins found in Membranoptera alata. Membranoptera alata is fertile in the winter months.

Listed by

- none -

Further information sources

Search on:


  1. Dickinson, C.I., 1963. British seaweeds. London & Frome: Butler & Tanner Ltd.

  2. Fish, J.D. & Fish, S., 1996. A student's guide to the seashore. Cambridge: Cambridge University Press.

  3. Hiscock, S., 1986b. A field key to the British Red Seaweeds. Taunton: Field Studies Council. [Occasional Publication No.13]

  4. Howson, C.M. & Picton, B.E., 1997. The species directory of the marine fauna and flora of the British Isles and surrounding seas. Belfast: Ulster Museum. [Ulster Museum publication, no. 276.]

  5. JNCC (Joint Nature Conservation Committee), 1999. Marine Environment Resource Mapping And Information Database (MERMAID): Marine Nature Conservation Review Survey Database. [on-line]

  6. Maggs, C.A. & Hommersand, M.H., 1993. Seaweeds of the British Isles: Volume 1 Rhodophycota Part 3A Ceramiales. London: Natural History Museum, Her Majesty's Stationary Office.

  7. National Biodiversity Network (NBN) Atlas website. Available from:  Accessed 01 April 2017

  8. Picton, B.E. & Costello, M.J., 1998. BioMar biotope viewer: a guide to marine habitats, fauna and flora of Britain and Ireland. [CD-ROM] Environmental Sciences Unit, Trinity College, Dublin.


This review can be cited as:

Edwards, R.V. 2003. Membranoptera alata A red seaweed. In Tyler-Walters H. and Hiscock K. (eds) Marine Life Information Network: Biology and Sensitivity Key Information Reviews, [on-line]. Plymouth: Marine Biological Association of the United Kingdom. [cited 16-08-2018]. Available from:

Last Updated: 29/08/2003