Polysiphonia ceramiaeformis, also called banded siphon weed, is a small red algae (Rhodophyta), in the genus Polysiphonia. Individuals are irregularly branched with the branches extending up to from a central node and ending in dense tufts of fibres.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 This small red algae lacks a clearly to be seen main axis. Each branch is formed of axial cells with 10 - 12 periaxial cells of equal length, with forcipate incurved tips.Jones, W.E. 1964(4) A key to the genera of the British seaweeds. Field studies (reprinted pp 1-32 It is densely branched and attached by tangled prostrate axes. All axes are ecorticate. The rhizoids are numerous
Reproduction The plants are dioecious. The alga bears spermatangial branches on a cylindrical axis. Cystocarps are oval with a narrow ostiole. The tetraspores cells divide to forms cells in fours, these occur in a spiral series.
Habitat In pools at low water in sheltered sites.
Distribution Very rare on the British Isles.Hardy, F.G. and Guiry, M.D. 2003. A Check-list and Atlas of the Seaweeds of Britain and Ireland. The British Phycological Society. Recorded from a few sites in Dorset,Batters, E.A.L. 1902. A Catalogue of The British Marine Algae. supplement to Journal of Botany 1902 pp.80 - 81 also recorded from north west France and the Mediterranean.
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