Vertebrata lanosa on Ascophyllum nodosum

''Polysiphonia lanosa'' (''Vertebrata lanosa'';Bunker, F.StP.D., Maggs, C.A., Brodie, J.A. and Bunker, A.R. 2017 ''Seaweeds of Britain and Ireland.'' Second Edition. Wild Nature Press, Plymouth Press, UK. ''Polysiphonia fastigiata'') is a common species of the red algae (

Rhodophyta Red algae, or Rhodophyta (, ; ), make up one of the oldest groups of eukaryotic algae. The Rhodophyta comprises one of the largest phyla of algae, containing over 7,000 recognized species within over 900 genera amidst ongoing taxonomic revisions. ...

) often to be found growing on ''

Ascophyllum nodosum ''Ascophyllum nodosum'' is a large, common cold water seaweed or brown alga ( Phaeophyceae) in the family Fucaceae. Its common names include knotted wrack, egg wrack, feamainn bhuí, rockweed, knotted kelp and Norwegian kelp. It grows only in the ...

''.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

The

thalli Thallus (: thalli), from Latinized Greek (), meaning "a green shoot" or "twig", is the vegetative tissue of some organisms in diverse groups such as algae, fungi, some liverworts, lichens, and the Myxogastria. A thallus usually names the entir ...

of this species form dense tufts, each tuft up to 7.5 cm generally attached by

rhizoid 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 un ...

s to the fronds of ''

Ascophyllum ''Ascophyllum nodosum'' is a large, common cold water seaweed or Phaeophyceae, brown alga (Phaeophyceae) in the Family (biology), family Fucaceae. Its common names include knotted wrack, egg wrack, feamainn bhuí, rockweed, knotted kelp and Norweg ...

''. The erect cylindrical branches divide pseudodichotomously, that is forming two equal branches, one of the branches growing from a lateral branch. A transverse section shows an axial cell surrounded by 12 to 24 peraxial cells. The axial cell is large and occupies about one third of the diameter of each branch, best seen in transverse section. It is deep brownish red in colour. '' Choreocolax polysiphoniae'' is a small

parasitic Parasitism is a close relationship between species, where one organism, the parasite, lives (at least some of the time) on or inside another organism, the host, causing it some harm, and is adapted structurally to this way of life. The ent ...

alga which grows in a cushion-like manner to 1 mm in diameter on the branches of ''P. lanosa''.

Habitat

Widespread growing

epiphytic An epiphyte is a plant or plant-like organism that grows on the surface of another plant and derives its moisture and nutrients from the air, rain, water (in marine environments) or from debris accumulating around it. The plants on which epiphyt ...

ally on ''Ascophyllum nodosum'' wherever it is found and occasionally on other species of ''

Fucus ''Fucus'' is a genus of brown algae found in the intertidal zones of rocky seashores almost throughout the world. Description and life cycle The thallus is perennial with an irregular or disc-shaped holdfast or with haptera. The erect portion ...

''.

Reproduction

The life history is a sequence of three phases:

gametangia A gametangium (: gametangia) is a sex organ or cell in which gametes are produced that is found in many multicellular protist A protist ( ) or protoctist is any eukaryotic organism that is not an animal, land plant, or fungus. Protists ...

carposporangia A carpospore is a diploid spore produced by red algae. After fertilization, the alga's carpogonium The carpogonium (plural ''carpogonia'') is the female organ in the red algae (Rhodophyta) which have a highly specialized type of reproduction. It ...

l and

tetrasporangia Red algae, or Rhodophyta (, ; ), make up one of the oldest groups of eukaryotic algae. The Rhodophyta comprises one of the largest phyla of algae, containing over 7,000 recognized species within over 900 genera amidst ongoing taxonomic revisions. ...

l. Two of the phases are similar. The plants are

dioecious Dioecy ( ; ; adj. dioecious, ) is a characteristic of certain species that have distinct unisexual individuals, each producing either male or female gametes, either directly (in animals) or indirectly (in seed plants). Dioecious reproduction is ...

with spermatangial branches produced in tufts at the apices of the branches. The

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 pr ...

s are borne, usually singly. with a narrow ostiole from which

carpospore A carpospore is a diploid spore produced by red algae Red algae, or Rhodophyta (, ; ), make up one of the oldest groups of eukaryotic algae. The Rhodophyta comprises one of the largest Phylum, phyla of algae, containing over 7,000 recognized spe ...

s are released. The tetraspores occur in spiral series resulting from a simultaneous division into 4 equal spores.Irvine, L. M. 1983. p.101 ''Seaweeds of the British Isles Volume 1 Rhodophyta Part 2A Cryptonemiales (sensu stricto) Palmeriales,'' Rhodymeniales. (British Museum)

Distribution

Common around the

British Isles The British Isles are an archipelago in the Atlantic Ocean, 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 Hebrides, Inner and Outer Hebr ...

and on the shores of

Europe Europe is a continent located entirely in the Northern Hemisphere and mostly in the Eastern Hemisphere. It is bordered by the Arctic Ocean to the north, the Atlantic Ocean to the west, the Mediterranean Sea to the south, and Asia to the east ...

from

Iceland Iceland is a Nordic countries, Nordic island country between the Atlantic Ocean, North Atlantic and Arctic Oceans, on the Mid-Atlantic Ridge between North America and Europe. It is culturally and politically linked with Europe and is the regi ...

Norway Norway, officially the Kingdom of Norway, is a Nordic countries, Nordic country located on the Scandinavian Peninsula in Northern Europe. The remote Arctic island of Jan Mayen and the archipelago of Svalbard also form part of the Kingdom of ...

Spain Spain, or the Kingdom of Spain, is a country in Southern Europe, Southern and Western Europe with territories in North Africa. Featuring the Punta de Tarifa, southernmost point of continental Europe, it is the largest country in Southern Eur ...

. Also

Greenland Greenland is an autonomous territory in the Danish Realm, Kingdom of Denmark. It is by far the largest geographically of three constituent parts of the kingdom; the other two are metropolitan Denmark and the Faroe Islands. Citizens of Greenlan ...

and

Newfoundland Newfoundland and Labrador is the easternmost province of Canada, in the country's Atlantic region. The province comprises the island of Newfoundland and the continental region of Labrador, having a total size of . As of 2025 the population ...

New England New England is a region consisting of six states in the Northeastern United States: Connecticut, Maine, Massachusetts, New Hampshire, Rhode Island, and Vermont. It is bordered by the state of New York (state), New York to the west and by the ...

References

{{Taxonbar, from=Q3556236 Rhodomelaceae