Polysiphonia stricta is a small red marine alga in the Division Rhodophyta.
Polysiphonia stricta forms dense clumps of branching axes. The plants grow to 25 cm high.Seaweeds of the British Isles Volume 1 Rhodophyta Part 3A Ceramiales. The Natural History Museum, London.
Description P. stricta grows as small tufts of much branched tufts, growing to no more than 25 cm high. The axes are erect, ecorticate, with 4 periaxial cells growing from prostrate axes. All 4 of the periaxial cells are of the same length.Bunker, F.StP. D., Brodie, J.A., Maggs, C.A. & Bunker, A.R. 2017. Seaweeds of Britain and Ireland. Second Edition. Wild Nature Press, Plymouth, UK.
Reproduction Spermatangial branchlets are formed in clusters at the apices. Cystocarps are on wide stalks and are urceolate. The tetraspores are in series in the final branches.
Habitat Epizoic and epiphytic in the low littoral to 20 m.
Distribution Found around the British Isles, the West Atlantic and American Atlantic.
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