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

A red seaweed (Phycodrys rubens)

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



A small red alga, up to 15 cm tall, with a leaf-like frond, with midrib, lateral veins and serrated margin that give the impression of an oak leaf. The disc-like holdfast gives rise to a short toughened stipe. In winter the frond wears away due to a combination of cessation of growth and wave action, leaving just the mid-rib, the blade growing back in spring. Phycodrys rubens is light crimson in colour and can be distinguished from the similarly leaf-like Delesseria sanguinea by the deeply serrated frond and branching habit.

Recorded distribution in Britain and Ireland

Commonly sublittoral present on rocky substrata in northern Britain but more widely distributed on kelp stipes. Absent from parts of the east coast where turbid waters and a lack of suitable substrata preclude its growth.

Global distribution



It is common in lower shore rock pools and the subtidal, growing on both rock and on the stipes of Laminaria hyperborea to a depth of up to 30 m.

Depth range


Identifying features

  • Up to 15 cm tall.
  • Leaf-like frond suggestive of an oak leaf and deeply serrated.
  • Disc-like holdfast.
  • Light crimson in colour.
  • Fronds have a branching habit.

Additional information

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Further information sources

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  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. Hardy, F.G. & Guiry, M.D., 2003. A check-list and atlas of the seaweeds of Britain and Ireland. London: British Phycological Society

  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. Norton, T.A. (ed.), 1985. Provisional Atlas of the Marine Algae of Britain and Ireland. Huntingdon: Biological Records Centre, Institute of Terrestrial Ecology.


This review can be cited as:

Pizzolla, P.F 2007. Phycodrys rubens 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 17-08-2018]. Available from:

Last Updated: 07/06/2007