''Polysiphonia denudata'' (''Polysiphonia variegate'' (C.Agardh) Zanardini) is a small red alga,
Rhodophyta
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 ...
, growing as tufts up to 20 cm long without a main branch axis.
[Maggs, C.A. and Hommersand, M.H. ''Seaweeds of the British Isles. Volume 1 Rhodophyta Part 3A Ceramiales'' The Natural History Museum, London]
Description
''Polysiphonia denudata'' is erect with repeatedly branched axes. Each branch consists of a central axis with 5 to 7 elongated pericentral cells all of the same length. Cortication occurs lower down, these corticating cells grow down in the grooves between the pericentral cells. The holdfast is discoid.
Reproduction
The plants are dioecious. They bear spermatangia towards the tips of 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 carpospores are released.Maggs, C.A. and Hom ...
s are barrel-shaped when mature borne on a wide short stalk. Tetrasporangia occur in a spiral series in the branches near the tips.
Habitat
The alga is very rare, grows on rock, stones or other large algae in the low-littoral or below in sheltered sites.
Distribution
Reported from the north of
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 1847, the specimen is in store in the
Ulster Museum
The Ulster Museum, located in the Botanic Gardens in Belfast, has around 8,000 square metres (90,000 sq. ft.) of public display space, featuring material from the collections of fine art and applied art, archaeology, ethnography, treas ...
, Belfast in
England
England is a country that is part of the United Kingdom. It shares land borders with Wales to its west and Scotland to its north. The Irish Sea lies northwest and the Celtic Sea to the southwest. It is separated from continental Europe ...
from the south coast,
[Batters, E.A.L. 1902. A Catalogue of the British Marine Algae. supplement to the ''Journal of Botany'' 40:1 - 107] Scottish records considered misidentifications,
[Hardy, F.G.and Guiry, M.D. 2003. ''A Check-list and Atlas of the Seaweeds of Britain and Ireland.'' British Phycological Society. ] Netherlands to Portugal and West Africa. The Mediterranean and west Atlantic.
References
Further References
Bunker, F.StP.D., Maggs,C.A., Brodie, J.A., Bunker, A.R. 2017. ''Seaweeds of Britain and Ireland.'' Second Edition. Wild Nature Press, Plymouth. UK.
{{Taxonbar, from=Q30591725
Rhodomelaceae