''Polysiphonia fibrillosa'' (Dillwyn) Sprengel is a species of marine

red alga Red algae, or Rhodophyta (, ; ), are one of the oldest groups of eukaryotic algae. The Rhodophyta also comprises one of the largest phyla of algae, containing over 7,000 currently recognized species with taxonomic revisions ongoing. The majority ...

in the Rhodophyta.

Description

''Polysiphonia fibrillose'' is a fine red alga which grows to 25 cm long. The erect cylindrical branches are themselves branched and are attached by a discoid holdfast. The branches consist of a central axis of cells each surrounded by 4 (or 5) pericentral cells of equal length and all elongate and of the same length. Corticating filaments grow down in the grooves between the pericentral cells.

Rhizoids Rhizoids are protuberances that extend from the lower epidermal cells of bryophytes and algae. They are similar in structure and function to the root hairs of vascular land plants. Similar structures are formed by some fungi. Rhizoids may be uni ...

grow from the pericentral cells. Trichoblasts are numerous.Maggs, C.A. and Hommersand, M.H. 1993. ''Seaweeds of the British Isles''. Volume 1 Rhodophyta Part 3A. The Natural History Museum, London. Other similar species include: ''P. rhunensis'' Thuret et Bornet, ''P.orthocarpa'' Rosenvinge. ''P.sertularioides'' and ''P.sanguinea'' C.Agardh.

Reproduction

The plants are dioecious and bear spermatangia near the apices of the branches.

Cystocarp A cystocarp is the fruiting structure produced in the red algae after fertilization, especially such a structure having a special protective envelope (as in '' Polysiphonia)''. The structure from which carpospore A carpospore is a diploid spore p ...

s are ovoid or globular and tetrasporangia are formed in series near the apices.

Habitat

Common on rocky shores both in the littoral to the sublittoral 10 m or more. Also grows epiphytically,Hardy, F.G. and Guiry, M.D. 2003. ''A Check-list and Atlas of the Seaweeds of Britain and Ireland.'' British Phycological Society.

Distribution

The species is widespread around

Great Britain Great Britain is an island in the North Atlantic Ocean off the northwest coast of continental Europe. With an area of , it is the largest of the British Isles, the largest European island and the ninth-largest island in the world. It i ...

, including Shetland, and

Ireland Ireland ( ; ga, Éire ; Ulster Scots dialect, Ulster-Scots: ) is an island in the Atlantic Ocean, North Atlantic Ocean, in Northwestern Europe, north-western Europe. It is separated from Great Britain to its east by the North Channel (Grea ...

. In Europe it is recorded from

Norway Norway, officially the Kingdom of Norway, is a Nordic country in Northern Europe, the mainland territory of which comprises the western and northernmost portion of the Scandinavian Peninsula. The remote Arctic island of Jan Mayen and the ...

, the Baltic and

France France (), officially the French Republic ( ), is a country primarily located in Western Europe. It also comprises of overseas regions and territories in the Americas and the Atlantic, Pacific and Indian Oceans. Its metropolitan area ...

References

Rhodomelaceae {{rhodophyta-stub