| Name | Notes |
|---|---|
| banded pincer weed | Ceramium virgatum (ceramiaceae) |
| Key criteria: | Large (to 15 cm) filamentous species growing both intertidally and in the shallow subtidal on sheltered to strongly wave-exposed shores in a wide range of habitats including rock pools. This species is very difficult to discriminate from closely related Ceramium species. The name (as C. rubrum then C. nodulosum) was widely used for all corticate species until recently and the recorded locations indicates this history. intertidal shallow subtidal subtidal rock sheltered exposed pool |
| twisted siphon weed | Polysiphonia nigra (rhodomelaceae) |
| Key criteria: | Fairly large (to 15 cm) polysiphonous species that consists of creeping and erect axes particularly in sandy habitats. It is relatively easy to identify. It is widespread and common in the area. sand |
| elongate siphon weed | Polysiphonia elongata (rhodomelaceae) |
| Key criteria: | Large (to 30 cm) much-branched polysiphonous species that grows in a wide range of habitats both on bedrock and on mobile substrata intertidally and subtidally. One of the most readily identifiable Polysiphonia species it is widespread and very common in the area and occurs northwards to Norway. intertidal subtidal rock |
| sand binder | Rhodothamniella floridula (rhodymeniaceae) |
| Key criteria: | Filamentous growths that often bind medium to coarse sand into large sandbanks on rocky coasts. Common and widespread on sand-affected shores. sand rock |
| bearded twig weed | Anotrichium barbatum (ceramiaceae) |
| Key criteria: | This distinctive filamentous species was recorded from southern England in the nineteenth century but was unknown in the twentieth century until it was discovered in North Wales at the sites shown. The Cornish record here is probably a misidentification of Anotrichium furcellatum known from southern England and western Wales and possibly introduced from the Pacific. ~ |
| forked twig weed | Anotrichium furcellatum (ceramiaceae) |
| Key criteria: | Probably alien filamentous species that was first noticed in the early 1980s initially confused with A. barbatum with which it is superficially similar. Fairly large (to 15 cm). Apparently still restricted in its UK distribution. Found in the lower intertidal and shallow subtidal at sheltered muddy sites. lower intertidal intertidal shallow subtidal subtidal mud sheltered |
| velvet threadweed | Bangia atropurpurea (bangiaceae) |
| Key criteria: | Microscopic to very small deep red brownish red or dark olive-green unbranched filaments up to 200 mm long. Upper intertidal and occasionally lower intertidal and subtidal. On rocks and wood pilings epiphytic and epizoic. When abundant it appears as velvet on rocks or boulders. epiphyte epizoic lower intertidal upper intertidal intertidal subtidal rock |
| tufted shrub weed | Boergeseniella fruticulosa (rhodomelaceae) |
| Key criteria: | Large (to 15 cm) polysiphonous species which occurs both subtidally and in intertidal pools in sandy and pebbly habitats. It is comparatively easy to identify. It is widespread the area but as shown here rare on eastern coasts of England and Scotland. intertidal subtidal sand pool |
| tufted conifer weed | Boergeseniella thuyoides (rhodomelaceae) |
| Key criteria: | Large (to 15 cm) polysiphonous species which is confined to the open intertidal mostly on wave-exposed shores. It is comparatively easy to identify microscopically but otherwise can be confused with Polysiphonia fucoides. It is widespread in the area but as shown here rare on eastern coasts of England and Scotland. intertidal exposed |
| alternate bush weed | Compsothamnion thuyoides (delesseriaceae) |
| Key criteria: | Large but delicate filamentous species found mostly subtidally where it is common on wave-exposed coasts growing epilithically. It is difficult to distinguish from C. thuyoides and is probably found on all coasts as indicated here. epilithic subtidal exposed |
| Mrs Griffiths' Devon weed | Griffithsia devoniensis (ceramiaceae) |
| Key criteria: | A small filamentous species fairly rare growing subtidally in sheltered and muddy habitats. It is not very easy to identify as it can be similar to the much more common species Halurus flosculosus. It is confined to the south-west of Britain and to southern Ireland and as shown here is particularly common in Milford Haven Pembrokeshire. subtidal mud sheltered |
| Atlantic siphon weed | Polysiphonia atlantica (rhodomelaceae) |
| Key criteria: | Small (to 3 cm) finely branched tufts that are confined to the intertidal zone of wave-exposed shores. Until recently its identification features were not well known and its restriction to southern and western coasts is not indicated in the records. Most records here are probably of Polysiphonia stricta a common and widespread species. intertidal exposed |
| Brodie's siphon weed | Polysiphonia brodiei (rhodomelaceae) |
| Key criteria: | Large (to 15 cm) much-branched polysiphonous species that is very common in the intertidal zone of exposed shores and also frequent on floating structures. It is widespread in the area and the lack of records here from south-east England is probably misidentifications. intertidal exposed |
| banded siphon weed | Polysiphonia ceramiaeformis (rhodomelaceae) |
| Key criteria: | Small (to 8 cm) polysiphonous species that is very rare in the area confined to the intertidal on south-western coasts. intertidal |
| wide branched siphon weed | Polysiphonia denudata (rhodomelaceae) |
| Key criteria: | Large (to 15 cm) branched polysiphonous species that is occurs relatively rarely in the subtidal zone of sheltered coasts and occasionally on floating structures. It is confined to south-western coasts and the Scottish records shown here are difficult to understand. subtidal sheltered |
| Devon siphon weed | Polysiphonia devoniensis (rhodomelaceae) |
| Key criteria: | Small (to 4 cm) finely branched polysiphonous species that is occurs very rarely on the lower shore and in the shallow subtidal of sheltered coasts. It is confined to south-western coasts. shallow subtidal subtidal sheltered |
| sandy siphon weed | Polysiphonia fibrata (rhodomelaceae) |
| Key criteria: | Small (to 8 cm) tufted polysiphonous species that is very common in the intertidal zone of exposed shores. It is easily recognizable microscopically when fertile but otherwise could be confused with several congeners. It is widespread in the area and the lack of records here from south-east England is presumably due to the lack of hard substrata. intertidal exposed |
| purple siphon weed | Polysiphonia fibrillosa (rhodomelaceae) |
| Key criteria: | Large (to 30 cm) polysiphonous species that is very common both intertidally and subtidally on sheltered and exposed shores. It is relatively easily recognizable. It is widespread in the area and appears to be under-recorded here. intertidal subtidal sheltered exposed |
| pungent siphon weed | Polysiphonia foetidissima (rhodomelaceae) |
| Key criteria: | Large (to 10 cm) very fine polysiphonous species that is very rare with the only two known twentieth-century records shown here. It appears to occur in sheltered subtidal habitats. subtidal sheltered |
| black siphon weed | Polysiphonia fucoides (rhodomelaceae) |
| Key criteria: | Large (to 30 cm) polysiphonous species with numerous lateral branches growing both intertidally and subtidally in a very wide range of habitats particularly common on damp intertidal bedrock. It is morphologically variable but relatively easy to identify. Its broad range of habitats and abundance are reflected in the very large number of records. intertidal subtidal rock |
| pincered siphon weed | Polysiphonia furcellata (rhodomelaceae) |
| Key criteria: | Fairly large (to 10 cm) finely branched polysiphonous species confined to the subtidal zone of sheltered shores. It is widely distributed but rare as shown here. subtidal sheltered |
| Harvey's siphon weed | Polysiphonia harveyi (rhodomelaceae) |
| Key criteria: | Fairly large (to 10 cm) much-branched polysiphonous species that is believed to be an alien introduction into the area. It is found in a wide variety of habitats from rock pools to the shallow subtidal where it grows epiphytically on algae and eelgrass. It appears to be more common on south-western coasts. epiphyte intertidal shallow subtidal rock pool |
| wrack siphon weed | Polysiphonia lanosa (rhodomelaceae) |
| Key criteria: | Fairly large (to 10 cm) much-branched polysiphonous species that grows obligately on fucoids particularly Ascophyllum nodosum. It is easily recognizable widespread and common in the area wherever the host algae occur. epiphyte |
| opaque siphon weed | Polysiphonia opaca (rhodomelaceae) |
| Key criteria: | Small (to 10 cm) polysiphonous species that is very rare on coasts of southern England and occurs southwards to Morocco. The records shown here are all questionable. ~ |
| similar siphon weed | Polysiphonia simulans (rhodomelaceae) |
| Key criteria: | Small (to 10 cm) polysiphonous species that is rare on coasts of southern England and occurs southwards to Morocco. Apparently restricted to the south coasts of England and Ireland most of the records shown here are questionable and are probably attributable to P. fucoides. ~ |
| pitcher siphon weed | Polysiphonia stricta (rhodomelaceae) |
| Key criteria: | Fairly large (to 50 cm) finely branched species growing both intertidally and subtidally in a very wide range of habitats particularly abundant subtidally on kelp stipes but also very common on intertidal bedrock. Its broad range of habitats and abundance are reflected in the very large number of records. intertidal subtidal rock |
| siphon weed | Polysiphonia subulifera (rhodomelaceae) |
| Key criteria: | Large (to 20 cm) polysiphonous species with regular lateral branching. Rare on coasts of southern England south and SW Ireland. Found only in on sheltered maerl beds or similar habitats. sheltered |
| parasitic winged weed | Pterosiphonia parasitica (rhodomelaceae) |
| Key criteria: | Small (to 8 cm) compressed polysiphonous species with regular laterals. Common in a wide variety of habitats both intertidally and subtidally epiphytic and epilithic throughout Britain and Ireland. Unlikely to be misidentified. epiphyte epilithic intertidal subtidal |
A Check-list and Atlas of the Seaweeds of Britain and Ireland. F. G. Hardy and M. D. Guiry. The British Phycological Society, 2003. ISBN 0 9527115 16 Seaweeds of Britain and Ireland. Bunker, Brodie, Maggs and Bunker. Seasearch 2012.