| Name | Notes |
|---|---|
| fuzzy branched weed | Arthocladia villosa (arthrocladiaceae) |
| Key criteria: | With its largely opposite branching and characteristic whorls of hair-like filaments this mainly epilithic summer annual is not uncommonly found on small stones etc. in the subtidal throughout the area. epilithic subtidal |
| slimy whip weed | Chordaria flagelliformis (chordariaceae) |
| Key criteria: | Plants common especially in the north. The branched cartilaginous thalli occur as a summer annual usually found in lower intertidal pools and in the subtidal. lower intertidal intertidal subtidal pool |
| Desmarest's prickly weed | Desmarestia aculeata (desmarestiaceae) |
| Key criteria: | Plants large and distinctive epilithic and mainly subtidal. Common and widely distributed. Spring and summer plants clothed in fascicles of hair-like filaments which are later shed leaving a serrated edge on winter plants. epilithic subtidal |
| no common name | Desmarestia dresnayi (desmarestiaceae) |
| Key criteria: | Plants large epilithic and subtidal forming simple erect delicate dorsiventrally flattened blades attached to small stones etc. in areas of moderate to strong water currents. A summer annual with a south-western and western distribution pattern. epilithic subtidal |
| Desmarest's flattened weed | Desmarestia ligulata (desmarestiaceae) |
| Key criteria: | A large very distinctive mainly subtidal plant widely distributed in the area although less common than Desmarestia aculeata. A summer annual. subtidal |
| Desmarest's green weed | Desmarestia viridis (desmarestiaceae) |
| Key criteria: | A fairly common and widely distributed spring and summer annual forming erect solitary much branched plants in lower intertidal pools and in the subtidal. lower intertidal intertidal subtidal pool |
| tubular net weed | Dictyosiphon foeniculaceus (chordariaceae) |
| Key criteria: | Plants common epiphytic or epilithic occurring as a summer annual in lower intertidal pools. Its apparent absence from the east coast of England requires further investigation. epiphyte epilithic lower intertidal intertidal pool |
| evenly divided branched weed | Spermatochnus paradoxus (chordariaceae) |
| Key criteria: | Plants not uncommon but apparently with a mainly western distribution pattern. A summer annual forming dichotomously branched cartilaginous thalli in muddy/sandy regions in the subtidal. subtidal mud sand |
| knobbly branched weed | Stilophora tenella (chordariaceae) |
| Key criteria: | Plants common showing a predominantly western distribution pattern. A summer annual found in the lower intertidal. lower intertidal intertidal |
| striped branched weed | Striaria attenuata (chordariaceae) |
| Key criteria: | Plants with a western distribution pattern forming distinctive branched terete thalli epiphytic on various algae in lower intertidal pools and in the shallow subtidal during the summer. epiphyte lower intertidal intertidal shallow subtidal subtidal pool |
| winged thread weed | Tilopteris mertensii (tilopteridaceae) |
| Key criteria: | A distinctive rare but widely distributed species in the lower intertidal and subtidal. lower intertidal 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.