''Polysiphonia atlantica'' is a small filamentous species of red marine
algae Rhodophyta. The thalli form small tufts up to 3 cm long. The axes are ecorticate consisting of axial cells surrounded by four periaxial cells.
[Maggs, C.A. and Hommersand, M.H. 1993 ''Seaweeds of the British Isles. Volume 1 Rhodophyta Part 3A Ceramiales.'' The Natural History Museum, London. ]
Description
''Polysiphonia atlantica'' is a small alga 3 cm high and dark reddish-brown in colour. It grows in tufts from prostrate axes producing numerous erect branches all growing to the similar lengths. The axial cells are surrounded by 4 periaxial cells which are elongate to the same length as the axial cells which are ecorticate. Attached by rhizoids produced by the periaxial cells.
Reproduction
The life history is a sequence of three phases: gametangial, carposporangial and tetrasporangial.
[Dixon, P.S. ''Biology of the Rhodophyta.'' p.187. Oliver & Boyd. ] The plants are dioecious with spermatangial branchlets at 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 slightly urceolate. The tetrasporangia occur the branches in a straight series.
Habitat
Growing on rock, mussels other invertebrates or epiphytic. Between high and low water levels.
[Hardy, F.G. and Guiry, M.D. 2003. ''A Check-list and Atlas of the Seaweeds of Britain and Ireland.'' The British Phycological Society. ]
Distribution
Records have been made from the
British Isles
The British Isles are a group of islands in the North Atlantic Ocean off the north-western coast of continental Europe, consisting of the islands of Great Britain, Ireland, the Isle of Man, the Inner and Outer Hebrides, the Northern Isles, ...
- England, Ireland, Wales and Scotland, to Morocco, east coast of America and the Indian Ocean.
Most of the records from the British Isles are probably those of ''Polysiphonia stricta''.
References
{{Taxonbar, from=Q25095718
Rhodomelaceae