| Name | Notes |
|---|---|
| callused drachiella | Drachiella heterocarpa (delesseriaceae) |
| Key criteria: | Small foliose species confined to the subtidal zone of wave-exposed coasts particularly subtidal cliffs. It can be confused with several other delesseriaceous algae. As shown here it has a western distribution in Britain and occurs up to the NE coast of Ireland (Rathlin I.) with scattered records from islands off western and northern Scotland. The records from SE Scotland and NE England require re-examination. subtidal exposed |
| rainbow weed or iridescent weed | Drachiella spectabilis (delesseriaceae) |
| Key criteria: | Large (to 15 cm) foliose species which is very conspicuous when young due to its bright blue iridescence. It is confined to the subtidal zone of wave-exposed coasts particularly subtidal cliffs. As shown here it has a south-western distribution in Britain and occurs up to the NE coast of Ireland (Rathlin I.) with scattered records from islands off western and northern Scotland. subtidal exposed |
| sea spider weed | Halarachnion ligulatum (furcellariaceae) |
| Key criteria: | Gametophytes are medium flattened blades undivided of irregularly dichotomously branched with marginal proliferations. Found on stones shells and maerl from 0-17m. Tetrasporophytes are crustose Cruoria-like growths found on small stones and maerl. Generally western distribution except for outlier population in north-eastern England. Common. ~ |
| polkadot weed | Haraldiophyllum bonnemaisonii (delesseriaceae) |
| Key criteria: | Large (to 20 cm) species with broad tattered blades growing primarily subtidally in a wide range of habitats with hard substratum most commonly on kelp stipes. It can be difficult to distinguish from several other delesseriaceous blades. It has a wide distribution in the area as shown here. subtidal |
| beautiful kidney weed | Kallymenia reniformis (kallymeniaceae) |
| Key criteria: | Medium-sized fronds of irregular shape sometimes with kidney-shaped proliferations or lobes. Upper subtidal to a depth of 35 m. Western distribution common. subtidal depth |
| mermaid's ear | Meredithia microphylla (kallymeniaceae) |
| Key criteria: | Small to medium ear-like cartilaginous fronds. Most common on subtidal ledges to a depth of 15 m. Western distribution occasional. subtidal depth |
| spotted scarf weed | Nitophyllum punctatum (delesseriaceae) |
| Key criteria: | Small to very large (to 50 cm) foliose species with broad much-branched blades. It grows mostly subtidally in a wide range of habitats. It can be confused with other delesseriaceous algae particularly Haraldiophyllum bonnemaisonii but is more common than the other similar species. It is particularly abundant in sheltered subtidal habitats as indicated but its abundance in western Scotland Orkney and Shetland. subtidal sheltered |
| sandy leaf bearer | Phyllophora crispa (phyllophoraceae) |
| Key criteria: | Medium crisped wedge-shaped compressed fronds often brittle and proliferous. In deep rock pools on rock occasionally on Laminaria hyperborea stipes from the lower intertidal to about 30 m. Tolerant of sand cover. Widely distributed and common. lower intertidal intertidal sand rock pool |
| northern pink | Porphyra amplissima (bangiaceae) |
| Key criteria: | Medium to large rose-pink to rose-red foliose alga. Shallow subtidal. Epiphytic on a variety of algae shells (e.g. Mytilus) and stones. It can be distinguished from P. drachii and P. leucosticta by its pink-red colour and the absence of pale lozenge/slit-shaped male sori. Confined to the northern parts of Britain and Ireland as reflected by the records. epiphyte shallow subtidal subtidal |
| black laver | Porphyra dioica (bangiaceae) |
| Key criteria: | Medium to large dark-olive-green to purple brown foliose alga. Epilithic on boulders which they can often dominate and pebbles in sand on wave-exposed shores or more exposed regions of sheltered shores. Common. epilithic sand sheltered exposed |
| kelp laver | Porphyra drachii (bangiaceae) |
| Key criteria: | Small dark red to purple foliose alga. Shallow subtidal. Epiphytic on frond tips of Laminaria hyperborea (Gunnerus) Foslie and epizoic on hydroids. Uncommon but possibly more widespread than indicated by records as it is easily overlooked. epiphyte epizoic shallow subtidal subtidal |
| pale patch laver | Porphyra leucosticta (bangiaceae) |
| Key criteria: | Small to medium chocolate brown purple-mauve to light brown foliose alga. Blade one cell layer thick variable in shape often ovate orbicular or umbilicate semi-translucent usually with ruffled margins. Lower intertidal to shallow subtidal. Epiphytic on other algae commonly Fucus serratus and Mastocarpus stellatus also on Laminaria hyperborea stipes and on shells (e.g. mussels) occasionally on pebbles. Common throughout. epiphyte lower intertidal intertidal shallow subtidal subtidal |
| winter laver | Porphyra linearis (bangiaceae) |
| Key criteria: | Small to medium brownish red to reddish purple foliose alga. Upper intertidal to above high water. Epilithic on bedrock boulders and also on concrete or wood and sea walls; amongst Fucus spiralis Pelvetia canaliculata on boulders with Ulva sheltered to semi-exposed. Winter annual. Common throughout. epilithic upper intertidal intertidal rock sheltered exposed |
| purple laver | Porphyra purpurea (bangiaceae) |
| Key criteria: | Medium to large reddish-brown to brown foliose alga. Lower to upper intertidal although principally mid-intertidal. Epilithic on bedrock boulders and pebbles often buried in sand; epizoic on barnacles limpets and mussels; occasionally epiphytic on Fucus; common on sheltered shores and extending up estuaries. On consolidated gravel and mussel beds often appearing like sheets of plastic food-wrap. Common throughout. epiphyte epilithic epizoic upper intertidal intertidal sand rock sheltered |
| rosy dew drops | Porphyropsis coccinea (erythrotrichiaceae) |
| Key criteria: | Small rose-pink foliose alga one cell layer thick arising from a cushion-like base. Thallus balloon-like when young expanding and splitting when mature. Lower intertidal and shallow subtidal. Epiphytic especially on Desmarestia aculeata and epizoic e.g. on the tube worm Tubularia. The species has a western and northern distribution. epiphyte epizoic lower intertidal intertidal shallow subtidal subtidal |
| flat winged weed | Pterosiphonia complanata (rhodomelaceae) |
| Key criteria: | Small (to 20 cm) compressed polysiphonous species with regular lateral branches. Fairly rare on wave-exposed coasts of south-west England and Ireland confined to the sublittoral fringe. Records from NE Ireland probably erroneous. exposed |
| shaded weed | Schottera nicaee_nsis (phyllophoraceae) |
| Key criteria: | Medium with relatively thin slightly wedge-shaped fronds with one or two dichotomies arising from a rhizomatous base. Seasonally variable in form; often with apical proliferations in late summer and early autumn. Shaded pools in the lower intertidal and on rock in the subtidal to a depth of 15 m. May be very common in the subtidal and is frequently associated with sponges. Widely distributed with a western distribution except for an outlier population in eastern England. Common. lower intertidal intertidal subtidal rock depth pool |
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.