| Name | Notes |
|---|---|
| creeping chain weed | Catenella caespitosa (caulacanthaceae) |
| Key criteria: | Small creeping fronds often aggregating into mats in the upper intertidal particularly on vertical surfaces under larger algae and in salt marshes. Widely distributed and common except for eastern England. upper intertidal intertidal marsh |
| Dumont's tubular weed | Dumontia contorta (dumontiaceae) |
| Key criteria: | Medium soft to lubricous fronds with basal branches and a twisted appearance. Mid to lower-intertidal pools most obvious in spring and early summer. Common and widespread. intertidal pool |
| clawed forkweed | Furcellaria lumbricalis (furcellariaceae) |
| Key criteria: | Medium cylindrical regularly dichotomous fronds. Very tolerant of sand cover. Large pools in lower intertidal to about 10 m. Common and widespread. lower intertidal intertidal sand pool |
| creephorn | Chondracanthus acicularis (gigartinaceae) |
| Key criteria: | Medium irregularly branched slightly compressed fronds forming entangled mats with arching reattaching branches. Pronounced south-western distribution. Lower intertidal and subtidal on rocks and cobble. Tolerant of sand cover. lower intertidal intertidal subtidal sand rock |
| black scour weed | Ahnfeltia plicata (ahnfeltiaceae ) |
| Key criteria: | Medium-sized wiry entangled alga with irregular branching. Common and widespread particularly in pools and on lower-shore rocks on sand-affected shores. sand rock pool |
| false eyelash weed | Calliblepharis jubata (cystocloniaceae) |
| Key criteria: | Similar to Calliblepharis ciliata narrower and with longer proliferations. Commoner in lower intertidal pools than C. ciliata and not extending greatly into the subtidal. Similar distribution to C.ciliata but more south-western in aspect. lower intertidal intertidal subtidal pool |
| no common name | Chondracanthus teedei (gigartinaceae) |
| Key criteria: | Medium regularly branched compressed fronds not mat-forming or reattaching. Silty sheltered shores in south-western England and Wales. sheltered |
| no common name | Corynophlaea crispa (chordariaceae) |
| Key criteria: | A small gelatinous epiphyte it forms hemispherical cushions on Chondrus crispus and appears to be largely confined to south-western and western coasts. A summer and autumn annual. epiphyte |
| purple claw weed | Cystoclonium purpureum (cystocloniaceae) |
| Key criteria: | Medium species with much-branched cylindrical fronds often forming proliferations. Mid-intertidal pools to depths of 24 m. Widespread and common. intertidal depth pool |
| pestle weed | Gigartina pistillata (gigartinaceae) |
| Key criteria: | Medium cylindrical cartilaginous fronds often regularly branched sometimes with slight compression. Found on sand-covered rocks generally at very low water. South-western distribution. Rare. sand rock |
| shepherd's purse wart weed | Gracilaria bursa-pastoris (gracilariaceae) |
| Key criteria: | Medium-sized fleshy species with somewhat brittle branches. Largely confined to the south coast of England where it is found in coastal lagoons and in sheltered pebble beaches in the lower intertidal. The two Irish locations may represent ephemeral introductions. lower intertidal intertidal sheltered |
| slender wart weed | Gracilaria gracilis (gracilariaceae) |
| Key criteria: | Medium-sized species with flexible branches and general elongated morphology. Readily confused with Gracilariopsis longissima for which we have only one submitted record (from Ireland). Widely distributed with a strong western bias. ~ |
| Grateoup's fern weed | Grateloupia filicina var. filicina (halymeniaceae) |
| Key criteria: | Medium-sized inconspicuous fronds with dichotomous or pinnate branches with little flattening. Mainly western distribution. Records from Kent and Norfolk require confirmation. Sandy pools in mid- to lower-intertidal. intertidal sand pool |
| red sea pine | Halopithys incurvus (rhodomelaceae) |
| Key criteria: | Large (to 30 cm) species with regularly branched cylindrical axes. Intertidal and shallow subtidal on bedrock. Very distinctive. It is confined to south and south-west England with a single confirmed record from Ireland. intertidal shallow subtidal subtidal rock |
| sea horsetail | Halurus equisetifolius (ceramiaceae) |
| Key criteria: | A large filamentous species with dense whorls of filaments around the main axes easily recognizable. It is fairly common subtidally on wave-exposed coasts and has a south-western distribution becoming much rarer northwards as shown here. The records here from Orkney and Yorkshire represent range extensions and require confirmation. subtidal exposed |
| rounded brittle fern weed | Laurencia obtusa (rhodomelaceae) |
| Key criteria: | Large (to 20 cm) species with branched cylindrical axes. Grows mostly in the shallow subtidal and mid-shore shallow pools. It is relatively uncommon but easily confused with the common species Osmundea hybrida unless examined fresh. It is primarily south-western and some records here from eastern Scotland and Shetland require re-examination. shallow subtidal subtidal pool |
| pyramidal fern weed | Laurencia pyramidalis (rhodomelaceae) |
| Key criteria: | Large (to 30 cm) intertidal species that is very rare and probably confined to extreme SW of the area probably just the Channel Islands. intertidal |
| Orkney bead weed | Lomentaria orcadensis (lomentariaceae) |
| Key criteria: | Small hollow strongly compressed mucilaginous but rather delicate fronds with small marginal proliferations. Epilithic on vertical rocks and in deep shaded pools in the lower intertidal to a depth of 20 m. Occasional on Laminaria hyperborea stipes. Widespread. epilithic lower intertidal intertidal rock depth pool |
| false pepper dulse | Osmundea hybrida (rhodomelaceae) |
| Key criteria: | Large (to 20 cm) species with branched cylindrical axes which is confined to the intertidal zone of sheltered to extremely exposed coasts. Growing on bedrock and pebbles. Can be confused with other members of the genus when non-reproductive. Its abundance and general distribution is reflected in the large number of records shown. intertidal rock sheltered exposed |
| brittle fern weed | Osmundea oederi (rhodomelaceae) |
| Key criteria: | Large (to 15 cm) species with branched compressed axes which is confined to the shallow subtidal zone of extremely sheltered to exposed coasts; intolerant of exposure to air. Growing on bedrock pebbles and epiphytically on fucoids. Can be confused with other members of the genus when non-reproductive particularly O. ramossisima. Very rare and with a south-western distribution. epiphyte shallow subtidal subtidal rock sheltered exposed |
| royal fern weed | Osmundea osmunda (rhodomelaceae) |
| Key criteria: | Large (to 30 cm) species with branched compressed axes. Grows mostly in the sublittoral fringe rarely deeper intolerant of exposure to air on bedrock. Previously confused with O. pinnatifida. Under-recorded here. rock |
| no common name | Osmundea ramosissima (rhodomelaceae) |
| Key criteria: | Large (to 15 cm) species with branched compressed axes which is confined to the intertidal zone of sheltered to extremely exposed coasts; intolerant of exposure to air. Growing on bedrock pebbles and epiphytically on fucoids. Can be confused with other members of the genus when non-reproductive. Relatively rare. epiphyte intertidal rock sheltered exposed |
| cock's comb | Plocamium cartilagineum (plocamiaceae) |
| Key criteria: | Small to medium with characteristic repeated one-sided apical branching. Lower-shore ledges (often tolerating sand) subtidal to 30 m. sometimes on Laminaria hyperborea stipes. Widespread and common. subtidal sand |
| discoid fork weed | Polyides rotundus (corallinaceae) |
| Key criteria: | Medium regularly and repeatedly cylindrical fronds arising from a small disk. Lower intertidal in large sandy pools and in the subtidal to 12 m. Widely distributed. Common. lower intertidal intertidal subtidal sand pool |
| branched wing weed | Pterocladiella capillacea (gelidiaceae) |
| Key criteria: | Distinctive medium-sized species found mainly on the sides or walls of deep pools in the intertidal where it persists for many years by means of stolons. Not known to reproduce other than by vegetative means. Predominantly western distribution. intertidal pool |
| straggly bush weed | Rhodomela confervoides (rhodomelaceae) |
| Key criteria: | Large (to 30 cm) cylindrical much- branched 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 |
| leafy rose weed | Rhodophyllis divaricata (cystocloniaceae) |
| Key criteria: | Small to medium species with irregularly dichotomously branched fronds often with proliferations. Generally subtidal to 30 m small plants occasional in deep lower- shore pools. Widely distributed except for large tracts of eastern Britain. Common subtidal pool |
| Solier's red string weed | Solieria chordalis (areschougiaceae) |
| Key criteria: | Probably introduced. Medium to large species with cylindrical rather brittle fronds. Lower intertidal to upper subtidal. Rare. Unknown in Ireland. lower intertidal intertidal subtidal |
| berry wart cress | Sphaerococcus coronopifolius (sphaerococcaceae) |
| Key criteria: | Gametophytes medium to large irregularly dichotomously divided compressed fronds arising from a small disk. Occasional in very large lower intertidal pools but mainly in shallow subtidal. Western distribution but more common in south-west. Sporophyte an extensive crust (Haematocelis fissurata) rarely reported in the subtidal. lower intertidal intertidal shallow subtidal subtidal pool |
| sparsley branched cock's comb | Plocamium subtile (plocamiaceae) |
| Key criteria: | Small to medium with characteristic repeated one-sided apical branching. Lower-shore ledges (often tolerating sand) subtidal to 30 m. sometimes on Laminaria hyperborea stipes. Widespread and common. subtidal sand |
| wiry cock's comb | Plocamium nanum (plocamiaceae) |
| Key criteria: | Small to medium with characteristic repeated one-sided apical branching. Lower-shore ledges (often tolerating sand) subtidal to 30 m. sometimes on Laminaria hyperborea stipes. Widespread and common. subtidal sand |
| Magg'scock's comb | Plocamium magsiae (plocamiaceae) |
| Key criteria: | Small to medium with characteristic repeated one-sided apical branching. Lower-shore ledges (often tolerating sand) subtidal to 30 m. sometimes on Laminaria hyperborea stipes. Widespread and common. subtidal sand |
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.