''Polysiphonia'' is a genus of filamentous

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 ...

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.Recorded common names are olann dhearg, craonach, cúnach triosgar, cluaisíní, mileara, millreacha, salata tou yialou (σαλάτα του γιαλού) and lobster horns. It is in the order

Ceramiales Ceramiales is an order of red algae. It was established by Friedrich Oltmanns in 1904. Families * Callithamniaceae Kützing, 1843 * Ceramiaceae Dumortier, 1822 * Choreocolacaceae Sturch * Dasyaceae Kützing, 1843 * Delesseriaceae Bory, 182 ...

and family

Rhodomelaceae Rhodomelaceae is estimated to be the largest red algae family, with about 125 genera and over 700 species. Included taxa Rhodomelaceae includes the following tribes and genera: ''Incertae sedis ' () or ''problematica'' is a term used fo ...

Description

''Polysiphonia'' is a red algae,

polysiphonous Polysiphonous describes an algal Algae (; singular alga ) is an informal term for a large and diverse group of photosynthetic eukaryotic organisms. It is a polyphyletic grouping that includes species from multiple distinct clades. Included org ...

and usually well branched, with some plants reaching a length of about 30 cm. They are attached by rhizoids or

haptera A holdfast is a root-like structure that anchors aquatic sessile organisms, such as seaweed, other sessile algae, stalked crinoids, benthic cnidarians, and sponges, to the substrate. Holdfasts vary in shape and form depending on both the s ...

to a rocky surface or other alga. The thallus (tissue) consists of fine branched filaments each with a central axial filament supporting pericentral cells. The number of these pericentral cells (4–24) is used in identification. ''

Polysiphonia elongata ''Polysiphonia elongata'' is a small red marine algae in the Rhodophyta. Description ''Polysiphonia elongata'' is a small red alga which, unlike some other species of ''Polysiphonia'', does not grow as tufts. It has erect cylindrical main bran ...

'' shows a central axial cell with 4

periaxial {{Short pages monitor