''Polysiphonia ceramiaeformis'', also called banded siphon weed, is a small

red algae 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 ...

(''

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 ...

''), in the genus ''

Polysiphonia ''Polysiphonia'' is a genus of filamentous red algae with about 19 species on the coasts of the British Isles and about 200 species worldwide, including Crete in Greece, Antarctica and Greenland. Its members are known by a number of common names. ...

''. 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. It is densely branched and attached by tangled prostrate axes. All axes are ecorticate. The

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 unic ...

are numerous

Reproduction

The plants are

dioecious Dioecy (; ; adj. dioecious , ) is a characteristic of a species, meaning that it has distinct individual organisms (unisexual) that produce male or female gametes, either directly (in animals) or indirectly (in seed plants). Dioecious reproductio ...

. The alga bears spermatangial branches on a cylindrical axis.

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 prod ...

s 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 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, ...

.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 Dorset ( ; archaically: Dorsetshire , ) is a county in South West England on the English Channel coast. The ceremonial county comprises the unitary authority areas of Bournemouth, Christchurch and Poole and Dorset (unitary authority), Dors ...

,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 France (), officially the French Republic ( ), is a country primarily located in Western Europe. It also comprises of Overseas France, overseas regions and territories in the Americas and the Atlantic Ocean, Atlantic, Pacific Ocean, Pac ...

and the

Mediterranean The Mediterranean Sea is a sea connected to the Atlantic Ocean, surrounded by the Mediterranean Basin and almost completely enclosed by land: on the north by Western and Southern Europe and Anatolia, on the south by North Africa, and on the e ...

References

Rhodomelaceae {{rhodophyta-stub