Polysiphonia fibrata is a species of Polysiphonia that grows as small dense tufted and finely branched marine alga in the Rhodophyta.
Description The branches of P. fibrate are numerous and much interwoven forming tufts up to 20 cm long. They are fine, terete, cylindrical, erect and dull brownish-red in colour. The branches consist of a central axis with 4 pericentral cells all of the same length as the axial cells. The branches become corticated near the base. Rhizoids and trichoblasts are abundant.Maggs, C.A. and Hommersand, M.H. 1993. Seaweeds of the British Isles Volume 1 Rhodophyta Part 3A Ceramiales The Natural History Museum, London
Reproduction The plants are dioecious. Spermatangia are borne near the tips of the branches. The cystocarps are clearly shortly stalked. Tetrasporangia are formed in the branches near the tips.
Habitat To be found on rock, limpets, mussels and on other algae in rock pools at mid-tide and low water.
Distribution Common around Britain including Shetland and Ireland.Morton, O. 2003. The marine macroalgae of County Donegal, Ireland. Bulletin of the Irish Biogeographical Society. 27: p.85)Hardy, F.G. and Guiry, M.D. 2003. A Check-list and Atlas of the Seaweeds of Britain and Ireland. The British Phycological Society Also recorded from Spain, and France.
Note Other species are similar to P. fibrata and difficult to distinguish.
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