Seaweed descriptions and pictures of seaweeds of the north-eastern Atlantic
Here is a selection of 250 or so of the larger seaweeds from the north-eastern Atlanic, many of which occur in Norway, Britain, Ireland, Atlantic France and Spain, and in Portugal. Web pages have so far been completed for those with links (underlined). Please be patient while the descriptions and pictures are refined.
Suggestions for additions and corrections to Michael Guiry. Where there is no common name in brackets, we have not discovered a suitable one.
Identification guide for selected marine non-native species (National Museum Wales). (Download free PDF, about 3.5 Mb).
Brown algae (Kelps, wracks, etc.)
*=adventive (introduced) species
- Alaria esculenta (Dabberlocks, Wing Kelp, Murlins)
- Ascophyllum nodosum (Asco, Sea Whistle, Bladderwrack)
- Asperococcus fistulosus
- Asperococcus bullosus
- Bifurcaria bifurcata (Brown Tuning Fork Weed; Brown Forking Weed)
- Carpomitra costata
- Chorda filum (Dead Man's Bootlaces)
- Cladostephus spongiosus
- Colpomenia peregrina (Oyster Thief)
- Cystoseira baccata (Bushy Berry Wrack) (see Gongolaria baccata)
- Cystoseira nodicaulis (Rainbow Wrack) (see Gongolaria nodicaulis)
- Cystoseira tamariscifolia (Bushy Rainbow Wrack) now Ericaria selaginoides
- Desmarestia aculeata
- Dictyopteris polypodioides
- Dictyota dichotoma
- Elachista fucicola
- Elachista scutulata
- Ericaria selaginoides (Bushy Rainbow Wrack)
- Eudesme virescens
- Fucus ceranoides (Horned Wrack; Estuary Wrack)
- Fucus guiryi (Guiry's Wrack)
- Fucus serratus (Serrated Wrack)
- Fucus spiralis (Spiralled Wrack)
- Fucus vesiculosus (Bladderwrack)
- Gongolaria baccata (Bushy Berry Wrack)
- Gongolaria nodicaulis (Rainbow Wrack)
- Halidrys siliquosa (Podweed, Sea Oak)
- Himanthalia elongata (Thongweed, Buttonweed, Sea Sphagetti)
- Laminaria digitata (Kelp)
- Laminaria hyperborea (Forest Kelp, May Weed)
- Laminaria ochroleuca (Golden Kelp)
- Leathesia marina (Punctured Ball Weed)
- Litosiphon pusillus
- Mesogloia vermiculata
- Myrionema strangulans
- Padina pavonia (Peacock's Tail)
- Pelvetia canaliculata (Channeled wrack)
- Petalonia fascia (Sea Petals, Broad Leaf Weed)
- Pseudoralfsia verrucosa (Brown Limpet Paint)
- Pylaiella littoralis
- Ralfsia verrucosa (see Pseudoralfsia verrucosa)
- Saccharina latissima (Sugar Kelp; formerly Laminaria saccharina)
- Saccorhiza polyschides (Furbelows, Furbellows, Sea Hedgehog)
- * Sargassum muticum (Japweed, an alien species in Europe)
- Scytosiphon lomentaria
- Spermatochnus paradoxus
- Sphacelaria cirrosa
- Spongonema tomentosum
- Stragularia clavata
- Stypocaulon scoparium
- Taonia atomaria
- * Undaria pinantifida (Wakame)
Red algae (Dulse, Carrageen Moss, etc.)
*=adventive (introduced) species
- Acrosorium venulosum [also known as Acrosorium ciliolatum]
- Aglaothamnion sepositum
- Ahnfeltia plicata (Landlady's Wig; Black Scour Weed)
- Ahnfeltiopsis devoniensis (Devonshire Fan Weed)
- Apoglossum ruscifolium
- Asparagopsis armata (Harpoon weed, an alien species in Europe)
- Bangia fuscopurpurea
- Bonnemaisonia asparagoides (Native)
- *Bonnemaisonia hamifera (Bonnemaison's Hook Weed; an alien species in Europe)
- Bostrychia scorpioides
- * Botryocladia wrightii (Golden Membrane Weed)
- Brongniartella byssoides (Bronginart's Thread Weed)
- Calliblepharis ciliata
- Calliblepharis jubata (False Eylash Weed)
- Callophyllis laciniata; see Metacallophyllis laciniata
- Catenella caespitosa (Creeping Chain Weed)
- *Caulacanthus okamurae (Okamura's Pom-Pom Weed)
- Ceramium shuttleworthianum
- Ceramium virgatum (also known as Ceramium rubrum)
- Champia parvula
- Chondria capillaris (Slender Cartilage Weed)
- Chondria coerulescens (Iridescent Cartilage Weed)
- Chondria dasyphylla
- Chondrus crispus (Carrageen Moss, Irish Moss)
- Chondracanthus acicularis (Creephorn)
- * Chrysymenia wrightii see Botryocladia wrightii
- Chylocladia verticillata
- Colaconema caespitosum
- Corallina berteroi
- Corallina caespitosa - see Corallina berteroi
- Corallina officinalis (Corallina)
- Corallina elongata - see Ellisolandia elongata
- Cordylecladia erecta (Erect Clublet)
- Cryptopleura ramosa
- Cystoclonium purpureum (Purple Claw Weed)
- Dasya hutchinsiae
- *Dasysiphonia japonica (Introduced alien; Siphoned Japan Weed)
- Delesseria sanguinea
- Dilsea carnosa (False dulse)
- Drachiella spectabilis (Only subtidal)
- Dudresnaya verticillata (Mostly subtidal)
- Dumontia contorta (Dumont's Tubular Weed)
- Ellisolandia elongata (A smaller and less common species of Corallina)
- Erythrodermis traillii
- Erythroglossum laciniatum (Mostly subtidal)
- Furcellaria lumbricalis (Black Carrageeen; Clawed Fork Weed)
- Gastroclonium ovatum
- Gelidiella calcicola
- Gelidium pulchellum
- Gelidium pusillum
- Gelidium spinosum (Spiny Straggle Weed)
- Gigartina pistillata (Pestle Weed)
- Gloiosiphonia capillaris (Sticky Tube Weed)
- Gracilaria bursa-pastoris (Shepherd's Purse Wart Weed)
- Gracilaria gracilis (Slender Wart Weed)
- Gracilaria vermiculophylla (Worm Wart Weed)
- Grateloupia filicina (Grateloup's Fern Weed)
- Grateloupia turuturu (Devil's Tongue Weed)
- Griffithsia corallinoides
- Gymnogongrus crenulatus (Norwegian Fan Weed)
- Halarachnion ligulatum (Exclusively subtidal)
- Halopithys incurva [Halopitys incurvus]
- Halurus equisetifolius (Sea Horsetail)
- Halurus flosculosus (Mrs Griffiths's Little Flower)
- Helminthora divaricata
- *Heterosiphonia japonica (see Dasysiphonia japonica)
- Heterosiphonia plumosa (Siphoned Feather Weed)
- Hypoglossum hypoglossoides
- Hildenbrandia rubra
- Jania rubens
- Jania squamata (also known as Haliptylon squamatum)
- Kallymenia reniformis (Mainly subtidal)
- Laurencia obtusa
- Lithophyllum incrustans
- Lomentaria articulata
- Lomentaria clavellosa
- Lomentaria orcadensis (Orkney Bead-weed; Orkney Weed)
- Mastocarpus stellatus (Grape Pip Weed)
- Meredithia microphylla (Exclusively subtidal)
- Membranoptera alata
- Mesophyllum lichenoides (Pink Plates)
- Metacallophyllis laciniata (Hudson) A.Vergés & L.Le Gall (Fried-egg weed; Beautiful Fan Weed)
- Nemalion multifidum
- Nitophyllum punctatum
- Odonthalia dentata (Primarily subtidal, often in drift in northern areas)
- Osmundea hybrida (Rounded Fern-weed)
- Osmundea osmunda (Pepper Dulse; Royal Fern-weed)
- Osmundea pinnatifida (Pepper Dulse)
- Palmaria palmata (Dulse, Dillisk)
- Phycodrys rubens (Sea Oak)
- Phyllophora crispa
- Phyllophora pseudoceranoides (Stalked Leaf Bearer)
- Phyllophora sicula (Hand Leaf Bearer)
- Phymatolithon calcareum (Maërl, Coral beaches, Coral strands)
- Pikea californica (Pike's Weed) NEW!
- Plocamium cartilagineum (Cock's Comb; Red Comb Weed)
- Plocamium maggsiae (Maggs's Cock's Comb)
- Plumaria plumosa (Soft Feather Weed)
- Polyides rotundus (Discoid Fork Weed)
- Polyneura bonnemaisonii
- Polysiphonia elongata (Elongate Siphon Weed)
- Polysiphonia stricta
- Pterocladiella capillacea (formerly Pterocadia capillacea; Branched Wing Weed)
- Pterosiphonia parasitica
- Porphyra dioica (Nori, Laver, Sloke)
- Porphyra linearis (Nori, Laver)
- Porphyra umbilicalis (Nori, Laver)
- Porphyrostromium boryanum
- Pterothamnion plumula (Bushy Feather Weed)
- Pterosiphonia complanata
- Ptilota gunneri (Feathered Wing Weed)
- Pyropia leucosticta (Thuret) Neefus & J.Brodie (Porphyra leucosticta)
- Rhodomela confervoides (Straggly Bush Weed)
- Rhodomela lycopodioides (Straggly Tail Weed)
- Rhodothamniella floridula
- Rhodochorton purpureum
- Rhodophyllis invineorum (Great Rose Weed)
- Rhodymenia ardissonei (Spiky Rose Weed)
- Rhodymenia holmesii (Holmes's Rose Weed)
- Rhodymenia pseudopalmata (Rosy Fan weed)
- Solieria chordalis (Solier's Red String Weed)
- Schizymenia dubyi
- Schottera nicaeënsis
- Schmitzia hiscockiana
- Sphaerococcus coronopifolius (Berry Wart Cress)
- Sphondylothamnion multifidum (Whorled Bush Weed)
- Spyridia griffithsiana (Hairy Basket Weed)
- Stengoramma interruptum (Papery Fan Weed)
- Vertebrata lanosa
- Wildemania amplissima (Nori, Laver)
Green algae (Sea Lettuce, etc.)
*=adventive (introduced) species
- Cladophora rupestris
- Codium bursa (Green Sponge Ball)
- * Codium fragile (Spongeweed, Green Sea Fingers)
- Codium tomentosum (Spongeweed)
- Monostroma grevillei
- Prasiola stipitata
- Prasiola calophylla
- Spongomorpha aeruginosa
- Ulva compressa (A kind of Sea Lettuce; a compressed tube-like green alga)
- Ulva intestinalis (A kind of Sea Lettuce; a tube-like green alga)
- Ulva fenestrata (Sea Lettuce) (formerly known as Ulva lactuca in NE Atlantic)
- Ulva linza
- Ulva rigida (Sea Lettuce)
- Umbraulva dangeardii (Sea Lettuce, but olive-green in colour rather than grass-green and often with regular holes)
Seagrasses (A flowering plant, not an alga)
- Zostera marina (Eel Grass; Eelgrass; Seagrass)
Photographs on this page © M.D. Guiry
Last modified: March 20 2023
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