Skip to Content

Vertebrata lanosa (Linnaeus) T.Christensen

Fact Sheet (Download PDF)

Also known as Polysiphonia lanosa (Linnaeus) Tandy
Common name: Olann Dhearg (Irish).
Description: Cartilaginous, cylindrical, densely tufted, dark reddish-purple fronds, to 75 mm long, attached by creeping rhizoids with branches penetrating the host fronds of Ascophyllum nodosum. Repeatedly pseudodichotomously branched, apices pointed, widely forked. Large central siphon with 12-24 pericentral siphons, ecorticate, articulations shorter than broad.
Habitat: Hemiparasitic on Ascophyllum nodosum, more rarely on Fucus vesiculosus, never on rock (appearances can be deceptive as it can grow on old stalks of both species) in the sheltered midtidal, generally distributed, usually abundant where Ascophyllum occurs.Vertebrata is gnerally infected with a tiny, more or less colourless parasitic red alga called Choreocolax polysiphoniae, to which it is closely related.


Species list

Photographs © M.D. Guiry

  • Bio AtlantisBioAtlantis provides sustainable technologies from the sea to enhance plant, animal and human health.
  • Connemara Organic Seaweed CompanyConnemara Organic Seaweed Company provide hand harvested, sustainable, kelp and seaweed products for human consumption through health supplements and edible products.
  • Emerald Isle Organic Irish SeaweedEmerald Isle Organic Irish Seaweed. A family business producing seaweed as supplements, cooking, gardening and bath products.
  • Irish Seaweeds LtdIrish Seaweeds Ltd are suppliers of 100% natural hand-harvested seaweeds and edible sea vegetable products from Ireland.