Penny weed (Zanardinia typus)

Distribution data supplied by the Ocean Biodiversity Information System (OBIS). To interrogate UK data visit the NBN Atlas.Map Help



Zanardinia typus is a fairly small brown seaweed with flat fronds that may be either round or fan-like and possibly irregular in shape. The appearance may change with age, varying in colour from olive to dark brown or black and in texture from smooth to leathery. The edge of the fronds may be smooth or ruffled, and has a distinct fringe of hairs.

Recorded distribution in Britain and Ireland

Found on southern and western coasts of England and the south and south western coasts of Ireland.

Global distribution

Occurs in the Channel Islands, on east Atlantic coasts from France south to Morocco, in the Mediterranean and the Adriatic, and the Black Sea.


Found mainly on silty boulders or bedrock, rarely on living substrata, sublittorally from shallow water to about 20 m depth.

Depth range


Identifying features

  • Horizontal, flat fronds that may be round or fan-like.
  • Up to 20 cm across.
  • Margin of the fronds with a fringe of short hairs, 3-4 mm long.
  • Colour varies from olive to dark brown or black.
  • Texture varies from smooth to leathery.
  • Loosely attached to the substratum by rhizoids on the undersurface.

Additional information

The above taxonomy uses the recent species name given by Hardy & Guiry (2003). Howson & Picton (1997) used the name Zanardinia prototypus.

Until 1973 the most northern record of Zanardinia prototypus was in the Channel Islands where it was considered rare. It was first recorded in Britain in 1973 at a site in south Devon (Jephson et al, 1975). In 1982 it was reported at sites on the coasts of Cornwall, Devon, Lundy, Pembrokeshire, and southwest Ireland although no reproductive structures were seen (Hiscock & Maggs, 1982) but it has been rarely seen since (Keith Hiscock, pers comm.).

Listed by

- none -


  1. Fletcher, R.L., 1987. Seaweeds of the British Isles vol. 3. Fucophyceae (Phaeophyceae) Part 1. London: British Museum (Natural History).

  2. Guiry, M.D. & Nic Dhonncha, E., 2002. AlgaeBase. World Wide Web electronic publication,

  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. Hiscock, S. & Maggs, C.A., 1982. Notes on Irish Marine Algae - 6. Zanardinia prototypus (Nardo) Nardo (Phaeophyta). Irish Naturalists' Journal, 20, 414-416.

  5. 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.]

  6. Jephson, N.A., Fletcher, R.L. & Berryman, J., 1975. The occurrence of Zanardinia prototypus on the south coast of England. British Phycological Journal, 10, 253-255.


  1. NBN (National Biodiversity Network) Atlas. Available from:

  2. OBIS (Ocean Biodiversity Information System),  2024. Global map of species distribution using gridded data. Available from: Ocean Biogeographic Information System. Accessed: 2024-04-23


This review can be cited as:

Avant, P. 2006. Zanardinia typus Penny weed. In Tyler-Walters H. Marine Life Information Network: Biology and Sensitivity Key Information Reviews, [on-line]. Plymouth: Marine Biological Association of the United Kingdom. [cited 23-04-2024]. Available from:

Last Updated: 09/11/2006