» Species Ascophyllum nodosum (Linnaeus) Le Jolis, 1863
  » Species Ascophyllum canaliculatum (Linnaeus) Kuntze, 1891 accepted as Pelvetia canaliculata (Linnaeus) Decaisne & Thuret, 1845 (synonym)
  » Species Ascophyllum chondrophyllum (R.Brown ex Turner) Kuntze, 1891 accepted as Xiphophora chondrophylla (R.Brown ex Turner) Montagne ex Harvey, 1855 (synonym)
  » Species Ascophyllum compressum (J.Agardh) Kuntze, 1891 accepted as Silvetia compressa (J.Agardh) E.Serrão, T.O.Cho, S.M.Boo & Brawley, 1999 (synonym)
  » Species Ascophyllum constricta (J.Agardh) Kuntze, 1891 accepted as Axillariella constricta (Kützing) Gruber, 1896 (synonym)
  » Species Ascophyllum mackayi (Turner) Holmes & Batters, 1892 accepted as Ascophyllum nodosum f. mackayi (Turner) A.C.Mathieson & Dawes, 2017 (synonym)
  » Species Ascophyllum robertsonii (Batters) Batters, 1892 accepted as Ascophyllum nodosum (Linnaeus) Le Jolis, 1863 (synonym)

  » Species Fucus abnormis Stackhouse
  » Species Fucus antennulatus Raffeneau-Delile
  » Species Fucus antennulatus Raffeneau Delile
  » Species Fucus aphyllantos Gmelin
  » Species Fucus atomarius (Woodward) Bertoloni
  » Species Fucus bacciferus
  » Species Fucus botryoid Forssk.
  » Species Fucus capitatus Gmelin
  » Species Fucus capitatus Stackh.
  » Species Fucus capreolatus R.Brown
  » Species Fucus caranoides
  » Species Fucus ceranoides Linnaeus, 1753
  » Species Fucus cespitosus
  » Species Fucus chalonii Feldmann, 1941
  » Species Fucus confervicola Chamisso
  » Species Fucus conglobatus Turner
  » Species Fucus coriaceus Roussel, 1806
  » Species Fucus corrigerus Vahl
  » Species Fucus cottonii M.J.Wynne & Magne, 1991
  » Species Fucus cystocarpus C.Agardh
  » Species Fucus degenerativus (Arcich.) Richard
  » Species Fucus deustus 'Fl.Dan.'
  » Species Fucus diaphanus Esper, 1800
  » Species Fucus distichus Linnaeus, 1767
  » Species Fucus evesiculosus Bory de Saint-Vincent
  » Species Fucus exilis R.Brown
  » Species Fucus filiformis S.G.Gmelin, 1768
  » Species Fucus fistulosus Huds.
  » Species Fucus flabellum Bertoloni
  » Species Fucus fuecii De la Pylaie
  » Species Fucus fungosus Desf.
  » Species Fucus funiformis Gunnerus
  » Species Fucus guiryi Zardi, Nicastro, E.S.Serrão & G.A.Pearson, 2011
  » Species Fucus heterophyllus C.L.Willdenow, 1794
  » Species Fucus radicans L.Bergström & L.Kautsky, 2005
  » Species Fucus serratus Linnaeus, 1753
  » Species Fucus sherardii
  » Species Fucus spiralis Linnaeus, 1753
  » Species Fucus tremella
  » Species Fucus vesiculosus Linnaeus, 1753
  » Species Fucus virsoides J.Agardh, 1868
  » Species Fucus abies-marinus S.G.Gmelin, 1768 accepted as Cystoseira abies-marina (S.G.Gmelin) C.Agardh, 1820 (synonym)
  » Species Fucus abrotanifolius Linnaeus, 1753 accepted as Cystoseira foeniculacea (Linnaeus) Greville, 1830
  » Species Fucus abrotanoides S.G.Gmelin, 1768 accepted as Cystoseira baccata (S.G.Gmelin) P.C.Silva, 1952 (synonym)
  » Species Fucus abscissus Turner, 1819 accepted as Melanthalia abscissa (Turner) J.D.Hooker & Harvey, 1845
  » Species Fucus acanthophorus J.V.Lamouroux, 1805 accepted as Acanthophora spicifera (M.Vahl) Børgesen, 1910
  » Species Fucus acerosus Forsskål, 1775 accepted as Gelidiella acerosa (Forsskål) Feldmann & Hamel, 1934
  » Species Fucus acetabulus Gouan, 1815 accepted as Kallymenia reniformis (Turner) J.Agardh, 1842 (synonym)
  » Species Fucus acicularis Wulfen, 1803 accepted as Chondracanthus acicularis (Roth) Fredericq, 1993
  » Species Fucus acicularis Esper, 1800 accepted as Cystoclonium purpureum (Hudson) Batters, 1902
  » Species Fucus acinaria S.G.Gmelin, 1768 accepted as Sargassum acinarium (Linnaeus) Setchell, 1933 (synonym)
  » Species Fucus acinarius Linnaeus, 1753 accepted as Sargassum acinarium (Linnaeus) Setchell, 1933
  » Species Fucus aculeatus Linnaeus, 1763 accepted as Desmarestia aculeata (Linnaeus) J.V.Lamouroux, 1813
  » Species Fucus aculeatus Esper, 1798 accepted as Cystoseira usneoides (Linnaeus) M.Roberts, 1968
  » Species Fucus aeruginosus Turner, 1811 accepted as Gracilaria multipartita (Clemente) Harvey, 1846 (synonym)
  » Species Fucus agarum S.G.Gmelin, 1768 accepted as Agarum clathratum Dumortier, 1822
  » Species Fucus alatus Hudson, 1762 accepted as Membranoptera alata (Hudson) Stackhouse, 1809
  » Species Fucus albidus Esper, 1800 accepted as Gracilaria gracilis (Stackhouse) Steentoft, L.M.Irvine & Farnham, 1995
  » Species Fucus albus Hudson, 1762 accepted as Ahnfeltia plicata (Hudson) Fries, 1836
  » Species Fucus alveatus Turner, 1819 accepted as Psilophycus alveatus (Turner) W.A.Nelson, Leister & Hommersand, 2011 (synonym)
  » Species Fucus alveolatus Esper, 1799 accepted as Mastocarpus stellatus (Stackhouse) Guiry, 1984 (synonym)
  » Species Fucus amansii J.V.Lamouroux, 1805 accepted as Gelidium amansii (J.V.Lamouroux) J.V.Lamouroux, 1813
  » Species Fucus ambiguus Clemente, 1807 accepted as Dictyopteris polypodioides (A.P.De Candolle) J.V.Lamouroux, 1809
  » Species Fucus amphibius Hudson, 1778 accepted as Bostrychia scorpioides (Hudson) Montagne, 1842
  » Species Fucus anceps Harvey & Ward ex Carruthers, 1864 accepted as Fucus distichus subsp. anceps (Harvey & Ward ex Carruthers) H.T.Powell, 1957
  » Species Fucus angustifolius Turner, 1811 accepted as Sargassum angustifolium C.Agardh, 1820
  » Species Fucus anomalus Pallas, 1766 accepted as Sporochnus anomalus (Pallas) M.J.Wynne, 2003
  » Species Fucus antarcticus Chamisso, 1822 accepted as Durvillaea antarctica (Chamisso) Hariot, 1892
  » Species Fucus aquifolius Turner, 1807 accepted as Sargassum aquifolium (Turner) C.Agardh, 1820
  » Species Fucus arbuscula A.P.de Candolle, 1805 accepted as Bryopsis plumosa (Hudson) C.Agardh, 1823 (synonym)
  » Species Fucus areschougii Kjellman, 1890 accepted as Fucus spiralis Linnaeus, 1753
  » Species Fucus articulatus Forsskål, 1775 accepted as Hormophysa cuneiformis (J.F.Gmelin) P.C.Silva, 1987 (synonym)
  » Species Fucus articulatus (Hudson) Lightfoot, 1777 accepted as Lomentaria articulata (Hudson) Lyngbye, 1819 (synonym)
  » Species Fucus asparagoides Woodward, 1794 accepted as Bonnemaisonia asparagoides (Woodward) C.Agardh, 1822
  » Species Fucus asplenioides Esper, 1804 accepted as Ptilota asplenioides (Esper) C.Agardh, 1822
  » Species Fucus australis Sonder, 1845 accepted as Myriodesma quercifolium (Bory de Saint-Vincent) J.Agardh, 1848
  » Species Fucus axillaris J.Agardh, 1868 accepted as Fucus vesiculosus var. volubilis Goodenough & Woodward, 1797 (synonym)
  » Species Fucus axillaris R.Brown ex Turner, 1811 accepted as Seirococcus axillaris (R.Brown ex Turner) Greville, 1830
  » Species Fucus babingtonii Harvey, 1860 accepted as Silvetia babingtonii (Harvey) E.A.Serrão, T.O.Cho, S.M.Boo & Brawley, 1999
  » Species Fucus baccatus S.G.Gmelin, 1768 accepted as Cystoseira baccata (S.G.Gmelin) P.C.Silva, 1952
  » Species Fucus baccifer Turner, 1802 accepted as Sargassum natans (Linnaeus) Gaillon, 1828
  » Species Fucus baccularia Mertens, 1819 accepted as Sargassum baccularia (Mertens) C.Agardh, 1824
  » Species Fucus baillouviana S.G.Gmelin, 1768 accepted as Dasya baillouviana (S.G.Gmelin) Montagne, 1841
  » Species Fucus balticus C.Agardh, 1814 accepted as Fucus vesiculosus Linnaeus, 1753
  » Species Fucus bangii Hornemann, 1813 accepted as Phyllophora crispa (Hudson) P.S.Dixon, 1964
  » Species Fucus banksii Turner, 1808 accepted as Hormosira banksii (Turner) Decaisne, 1842
  » Species Fucus barbatus Goodenough & Woodward, 1797 accepted as Cystoseira barbata (Stackhouse) C.Agardh, 1820
  » Species Fucus barbatus Gunnerus, 1772 accepted as Devaleraea ramentacea (Linnaeus) Guiry, 1982
  » Species Fucus barbatus Linnaeus, 1753 accepted as Cystoseira foeniculacea (Linnaeus) Greville, 1830 (synonym)
  » Species Fucus bifidus Hudson, 1778 accepted as Rhodophyllis divaricata (Stackhouse) Papenfuss, 1950
  » Species Fucus bifidus S.G.Gmelin, 1768 accepted as Arthrothamnus bifidus (S.G.Gmelin) J.Agardh, 1868
  » Species Fucus bifurcatus Velley, 1792 accepted as Bifurcaria bifurcata R.Ross, 1958
  » Species Fucus bifurcatus Gunnerus, 1766 accepted as Laminaria digitata (Hudson) J.V.Lamouroux, 1813 (synonym)
  » Species Fucus biserratus Thunberg, 1815 accepted as Sargassum fulvellum (Turner) C.Agardh, 1820
  » Species Fucus botryocarpus Turner, 1819 accepted as Botryocarpa prolifera Greville, 1830
  » Species Fucus botryoides Wulfen, 1791 accepted as Botryocladia botryoides (Wulfen) Feldmann, 1941
  » Species Fucus botryoides Turner, 1811 accepted as Laurencia botryoides (C.Agardh) Gaillon, 1828
  » Species Fucus bracteatus S.G.Gmelin, 1768 accepted as Gigartina bracteata (S.G.Gmelin) Setchell & N.L.Gardner, 1933
  » Species Fucus brodiei Turner, 1809 accepted as Coccotylus brodiei (Turner) Kützing, 1843
  » Species Fucus brownii Turner, 1819 accepted as Cystophora brownii (Turner) J.Agardh, 1848
  » Species Fucus bryum Strøm, 1788 accepted as Cladostephus spongiosus (Hudson) C.Agardh, 1817
  » Species Fucus buccinalis Linnaeus, 1771 accepted as Ecklonia maxima (Osbeck) Papenfuss, 1940
  » Species Fucus bulbosus Hudson, 1778 accepted as Saccorhiza polyschides (Lightfoot) Batters, 1902
  » Species Fucus bullatus O.F.Müller, 1777 accepted as Palmaria palmata (Linnaeus) F.Weber & D.Mohr, 1805
  » Species Fucus bursa-pastoris S.G.Gmelin, 1768 accepted as Gracilaria bursa-pastoris (S.G.Gmelin) P.C.Silva, 1952 (synonym)
  » Species Fucus bursigerus J.Agardh, 1868 accepted as Fucus evanescens C.Agardh, 1820
  » Species Fucus bursus (Linnaeus) Turner, 1811 accepted as Codium bursa (Olivi) C.Agardh, 1817
  » Species Fucus byssoides Goodenough & Woodward, 1797 accepted as Vertebrata byssoides (Goodenough & Woodward) Kuntze, 1891
  » Species Fucus cabrerae Clemente, 1807 accepted as Carpomitra costata (Stackhouse) Batters, 1902
  » Species Fucus cactoides Turner, 1809 accepted as Caulerpa cactoides (Turner) C.Agardh, 1817
  » Species Fucus caespitosus Stackhouse, 1795 accepted as Gelidium corneum var. caespitosum (Turner) J.Agardh, 1851 (synonym)
  » Species Fucus canalicularioides Clemente, 1807 accepted as Liagora distenta (Mertens ex Roth) J.V.Lamouroux, 1816
  » Species Fucus canaliculatus Linnaeus, 1767 accepted as Pelvetia canaliculata (Linnaeus) Decaisne & Thuret, 1845 (synonym)
  » Species Fucus capensis S.G.Gemelin, 1768 accepted as Gelidium capense (S.G.Gmelin) P.C.Silva, 1987
  » Species Fucus capillaceus S.G.Gmelin, 1768 accepted as Pterocladiella capillacea (S.G.Gmelin) Santelices & Hommersand, 1997
  » Species Fucus capillaris Hudson, 1778 accepted as Gloiosiphonia capillaris (Hudson) Carmichael, 1833
  » Species Fucus caprinus Gunnerus, 1766 accepted as Polyides rotunda (Hudson) Gaillon, 1828
  » Species Fucus caprinus Vahl, 1794 accepted as Palmaria palmata (Linnaeus) F.Weber & D.Mohr, 1805
  » Species Fucus carnosus Schmidel, 1794 accepted as Dilsea carnosa (Schmidel) Kuntze, 1898
  » Species Fucus cartilagineus Linnaeus, 1753 accepted as Plocamium cartilagineum (Linnaeus) P.S.Dixon, 1967
  » Species Fucus cartilagineus Forsskål, 1775 accepted as Phycodrys rubens (Linnaeus) Batters, 1902
  » Species Fucus caudatus Labillardière, 1807 accepted as Perithalia caudata (Labillardière) Womersley, 1967
  » Species Fucus cephalornithos Labillardière, 1807 accepted as Caulocystis cephalornithos (Labillardière) J.E. Areschoug, 1854
  » Species Fucus cervicornis Turner, 1808 accepted as Gracilaria cervicornis (Turner) J.Agardh, 1852
  » Species Fucus chemnitzia Esper, 1800 accepted as Caulerpa chemnitzia (Esper) J.V.Lamouroux, 1809 (synonym)
  » Species Fucus chondrophyllus R.Brown ex Turner, 1819 accepted as Xiphophora chondrophylla (R.Brown ex Turner) Montagne ex Harvey, 1855
  » Species Fucus ciliatus Hudson, 1762 accepted as Calliblepharis ciliata (Hudson) Kützing, 1843
  » Species Fucus cirrhosus Turner, 1807 accepted as Plocamium cirrhosum (Turner) M.J.Wynne, 2002
  » Species Fucus clathrus S.G.Gmelin, 1768 accepted as Thalassiophyllum clathrus (S.G.Gmelin) Postels & Ruprecht, 1840 (synonym)
  » Species Fucus claudei Turner, 1811 accepted as Claudea elegans J.V.Lamouroux, 1813
  » Species Fucus clavatus J.V.Lamouroux, 1805 accepted as Gelidium clavatum (J.V.Lamouroux) J.V.Lamouroux, 1813
  » Species Fucus clavellosus Lightfoot ex Turner, 1802 accepted as Lomentaria clavellosa (Lightfoot ex Turner) Gaillon, 1828
  » Species Fucus clavifer Turner, 1807 accepted as Caulerpa racemosa (Forsskål) J.Agardh, 1873
  » Species Fucus coccineus Hudson, 1778 accepted as Plocamium cartilagineum (Linnaeus) P.S.Dixon, 1967 (synonym)
  » Species Fucus commersonii J.V.Lamouroux ex Montagne, 1847 accepted as Cystoseira myrica (S.G.Gmelin) C.Agardh, 1820 (synonym)
  » Species Fucus comosus Poiret, 1808 accepted as Sargassum desfontainesii (Turner) C.Agardh, 1820 (synonym)
  » Species Fucus comosus Labillardière, 1807 accepted as Phyllospora comosa (Labillardière) C.Agardh, 1839
  » Species Fucus complanatus Clemente, 1807 accepted as Pterosiphonia complanata (Clemente) Falkenberg, 1897
  » Species Fucus compressus Esper, 1799 accepted as Cystoseira compressa (Esper) Gerloff & Nizamuddin, 1975
  » Species Fucus compressus C.Agardh, 1824 accepted as Silvetia compressa (J.Agardh) E.Serrão, T.O.Cho, S.M.Boo & Brawley, 1999
  » Species Fucus concatenatus Linnaeus, 1753 accepted as Cystoseira foeniculacea (Linnaeus) Greville, 1830 (unaccepted)
  » Species Fucus concinnus R.Brown ex Turner, 1811 accepted as Trematocarpus concinnus (R.Brown ex Turner) De Toni, 1900 (unaccepted)
  » Species Fucus confertus R.Brown ex Turner, 1811 accepted as Leptophyllis conferta (R.Brown ex Turner) J.Agardh, 1876 (unaccepted)
  » Species Fucus confervoides Linnaeus, 1763 accepted as Gracilariopsis longissima (S.G.Gmelin) Steentoft, L.M.Irvine & Farnham, 1995 (unaccepted, synonym)
  » Species Fucus confervoides Hudson, 1762 accepted as Rhodomela confervoides (Hudson) P.C.Silva, 1952 (unaccepted)
  » Species Fucus confluens R.Brown ex Turner, 1811 accepted as Carpoglossum confluens (R.Brown ex Turner) Kützing, 1843 (unaccepted)
  » Species Fucus congestus R.Brown ex Turner, 1809 accepted as Areschougia congesta (R.Brown ex Turner) J.Agardh, 1872 (unaccepted)
  » Species Fucus constrictus Turner, 1809-1811 accepted as Polyopes constrictus (Turner) J.Agardh, 1851 (unaccepted)
  » Species Fucus constrictus Harvey, 1838 accepted as Axillariella constricta (Kützing) Gruber, 1896 (unaccepted)
  » Species Fucus contortus S.G.Gmelin, 1768 accepted as Dumontia contorta (S.G.Gmelin) Ruprecht, 1850 (unaccepted)
  » Species Fucus corallinus O.F.Müller, 1777 accepted as Cystoclonium purpureum (Hudson) Batters, 1902 (unaccepted)
  » Species Fucus coralloides Poiret, 1808 accepted as Hydropuntia edulis (S.G.Gmelin) Gurgel & Fredericq, 2004 (unaccepted)
  » Species Fucus corallorhiza Turner, 1808 accepted as Plocamium corallorhiza (Turner) J.D.Hooker & Harvey, 1845 (unaccepted)
  » Species Fucus cordatus Turner, 1809 accepted as Iridaea cordata (Turner) Bory, 1826 (unaccepted)
  » Species Fucus cornatus Linnaeus, 1771 accepted as Gelidium vittatum (Linnaeus) Kützing, 1843 (unaccepted)
  » Species Fucus corneus Hudson, 1762 accepted as Gelidium corneum (Hudson) J.V.Lamouroux, 1813 (unaccepted)
  » Species Fucus corneus Zoega, 1772 accepted as Chordaria flagelliformis (O.F.Müller) C.Agardh, 1817 (unaccepted)
  » Species Fucus corniculatus R.Brown ex Turner, 1811 accepted as Gracilaria corniculata (C.Agardh) J.Agardh, 1852 (unaccepted)
  » Species Fucus corniculatus Wulfen, 1786 accepted as Treptacantha abies-marina (S.G.Gmelin) Kützing, 1843 (unaccepted)
  » Species Fucus cornucopiae Mertens, 1829 accepted as Arthrothamnus bifidus (S.G.Gmelin) J.Agardh, 1868 (unaccepted)
  » Species Fucus cornutus Turner, 1811 accepted as Plocamium cornutum (Turner) Harvey, 1849 (unaccepted)
  » Species Fucus coronopifolius Zoega, 1772 accepted as Mastocarpus stellatus (Stackhouse) Guiry, 1984 (unaccepted)
  » Species Fucus coronopifolius Goodenough & Woodward, 1797 accepted as Sphaerococcus coronopifolius Stackhouse, 1797 (unaccepted)
  » Species Fucus corymbiferus S.G.Gmelin, 1768 accepted as Odonthalia corymbifera (S.G.Gmelin) Greville, 1830 (unaccepted)
  » Species Fucus costatus Stackhouse, 1802 accepted as Carpomitra costata (Stackhouse) Batters, 1902 (unaccepted)
  » Species Fucus costatus Turner, 1819 accepted as Costaria costata (C.Agardh) De A.Saunders, 1895 (unaccepted)
  » Species Fucus cottoni M.J.Wynne & Magne, 1991 accepted as Fucus cottonii M.J.Wynne & Magne, 1991 (unaccepted)
  » Species Fucus crassipes Mertens ex Turner, 1809 accepted as Stephanocystis crassipes (Mertens ex Turner) Draisma, Ballesteros, F.Rousseau & T.Thibaut, 2010 (unaccepted, synonym)
  » Species Fucus crenatus S.G.Gmelin, 1768 accepted as Phycodrys rubens (Linnaeus) Batters, 1902 (unaccepted)
  » Species Fucus crenulatus Turner, 1802 accepted as Gymnogongrus crenulatus (Turner) J.Agardh, 1851 (unaccepted)
  » Species Fucus cribrosus Mertens f., 1829 accepted as Agarum turneri Postels & Ruprecht, 1840 (unaccepted)
  » Species Fucus crinalis Hare ex Turner, 1819 accepted as Gelidium crinale (Hare ex Turner) Gaillon, 1828 (unaccepted)
  » Species Fucus crinitus Desfontaines, 1799 accepted as Cystoseira crinita Duby, 1830 (unaccepted, synonym)
  » Species Fucus crinitus S.G.Gmelin, 1768 accepted as Tichocarpus crinitus (S.G.Gmelin) Ruprecht, 1850 (unaccepted)
  » Species Fucus crispatus Hudson, 1778 accepted as Cryptopleura ramosa (Hudson) L.Newton, 1931 (unaccepted)
  » Species Fucus crispatus Linnaeus, 1767 accepted as Cryptopleura ramosa (Hudson) L.Newton, 1931 (unaccepted, synonym)
  » Species Fucus crispus Linnaeus, 1767 accepted as Chondrus crispus Stackhouse, 1797 (unaccepted, synonym)
  » Species Fucus crispus Hudson, 1762 accepted as Phyllophora crispa (Hudson) P.S.Dixon, 1964 (unaccepted)
  » Species Fucus crispus Forsskål, 1775 accepted as Sargassum notarisii Zanardini, 1858 (unaccepted)
  » Species Fucus cristatus Sommerfelt, 1826 accepted as Euthora cristata (C.Agardh) J.Agardh, 1847 (unaccepted)
  » Species Fucus cristatus Linnaeus ex Turner, 1808 accepted as Euthora cristata (C.Agardh) J.Agardh, 1847 (unaccepted, synonym)
  » Species Fucus cristatus Withering, 1796 accepted as Cryptopleura ramosa (Hudson) L.Newton, 1931 (unaccepted, synonym)
  » Species Fucus cuneiformis J.F.Gmelin, 1792 accepted as Hormophysa cuneiformis (J.F.Gmelin) P.C.Silva, 1987 (unaccepted)
  » Species Fucus cupressoides Vahl, 1802 accepted as Caulerpa cupressoides (Vahl) C.Agardh, 1817 (unaccepted)
  » Species Fucus cyanospermus Delile, 1813 accepted as Laurencia cyanosperma (Delile) Gaillon, 1828 (unaccepted)
  » Species Fucus cypellon Bertoloni, 1818 accepted as Phyllophora herediae (Clemente) J.Agardh, 1842 (unaccepted)
  » Species Fucus dasyphyllus Woodward, 1794 accepted as Chondria dasyphylla (Woodward) C.Agardh, 1817 (unaccepted, synonym)
  » Species Fucus debilis Forsskål, 1775 accepted as Gracilaria debilis (Forsskål) Børgesen, 1932 (unaccepted)
  » Species Fucus decipiens R.Brown ex Turner, 1811 accepted as Phyllotricha decipiens (R.Brown ex Turner) R.R.M.Dixon & Huisman, 2012 (unaccepted)
  » Species Fucus decurrens R.Brown ex Turner, 1811 accepted as Sargassopsis decurrens (R.Brown ex Turner) Trevisan, 1843 (unaccepted, synonym)
  » Species Fucus degener Esper, 1804 accepted as Mastocarpus stellatus (Stackhouse) Guiry, 1984 (unaccepted, synonym)
  » Species Fucus delicatulus (Gunnerus) Vahl, 1797 accepted as Palmaria palmata (Linnaeus) F.Weber & D.Mohr, 1805 (unaccepted)
  » Species Fucus dentatus Linnaeus, 1767 accepted as Odonthalia dentata (Linnaeus) Lyngbye, 1819 (unaccepted)
  » Species Fucus denticulatus N.L.Burman, 1768 accepted as Eucheuma denticulatum (N.L.Burman) Collins & Hervey, 1917 (unaccepted)
  » Species Fucus denticulatus Forsskål, 1775 accepted as Sargassum dentifolium (Turner) C.Agardh, 1820 (unaccepted)
  » Species Fucus dentifolius Turner, 1808 accepted as Sargassum dentifolium (Turner) C.Agardh, 1820 (unaccepted)
  » Species Fucus desfontainesii Turner, 1811 accepted as Sargassum desfontainesii (Turner) C.Agardh, 1820 (unaccepted)
  » Species Fucus desvauxii Mertens, 1819 accepted as Sargassum desvauxii (Mertens) C.Agardh, 1820 (unaccepted)
  » Species Fucus devoniensis Greville, 1821 accepted as Ahnfeltiopsis devoniensis (Greville) P.C.Silva & DeCew, 1992 (unaccepted, synonym)
  » Species Fucus dichotomus Lepechin, 1775 accepted as Fimbrifolium dichotomum (Lepechin) G.I.Hansen, 1980 (unaccepted)
  » Species Fucus dichotomus (Hudson) Bertoloni, 1819 accepted as Dictyota dichotoma (Hudson) J.V.Lamouroux, 1809 (unaccepted, synonym)
  » Species Fucus digitatus Hudson, 1762 accepted as Laminaria digitata (Hudson) J.V.Lamouroux, 1813 (unaccepted, synonym)
  » Species Fucus dilatatus Turner, 1811 accepted as Gymnogongrus dilatatus (Turner) J.Agardh, 1851 (unaccepted)
  » Species Fucus discors Linnaeus, 1767 accepted as Cystoseira foeniculacea (Linnaeus) Greville, 1830 (unaccepted)
  » Species Fucus distentus Mertens ex Roth, 1806 accepted as Liagora distenta (Mertens ex Roth) J.V.Lamouroux, 1816 (unaccepted)
  » Species Fucus divaricatus R.Brown ex Turner, 1809 accepted as Hymenocladia divaricata Harvey, 1855 (unaccepted)
  » Species Fucus divaricatus Linnaeus, 1753 accepted as Fucus vesiculosus Linnaeus, 1753 (unaccepted)
  » Species Fucus divergens J.Agardh, 1872 accepted as Fucus ceranoides Linnaeus, 1753 (unaccepted)
  » Species Fucus diversifolius Turner, 1800 accepted as Sargassum diversifolium (Turner) C.Agardh, 1824 (unaccepted)
  » Species Fucus dorycarpus Turner, 1809 accepted as Scytothalia dorycarpa (Turner) Greville, 1830 (unaccepted)
  » Species Fucus dulcis S.G.Gmelin, 1768 accepted as Palmaria palmata (Linnaeus) F.Weber & D.Mohr, 1805 (unaccepted)
  » Species Fucus echinatus Stackhouse, 1797 accepted as Mastocarpus stellatus (Stackhouse) Guiry, 1984 (unaccepted, synonym)
  » Species Fucus echinatus Poiret, 1808 accepted as Sarcothalia stiriata (Turner) Leister, 1993 (unaccepted, synonym)
  » Species Fucus edentatus Bachelot Pylaie, 1830 accepted as Fucus distichus subsp. edentatus (Bachelot Pylaie) H.T.Powell, 1957 (unaccepted)
  » Species Fucus edulis S.G.Gmelin, 1768 accepted as Hydropuntia edulis (S.G.Gmelin) Gurgel & Fredericq, 2004 (unaccepted, synonym)
  » Species Fucus edulis Stackhouse, 1801 accepted as Dilsea carnosa (Schmidel) Kuntze, 1898 (unaccepted)
  » Species Fucus elminthoides Velley, 1792 accepted as Nemalion elminthoides (Velley) Batters, 1902 (unaccepted)
  » Species Fucus elongatus Linnaeus, 1753 accepted as Himanthalia elongata (Linnaeus) S.F.Gray, 1821 (unaccepted)
  » Species Fucus elongatus Gunnerus, 1772 accepted as Cystoclonium purpureum (Hudson) Batters, 1902 (unaccepted)
  » Species Fucus endiviifolius Lightfoot, 1777 accepted as Cryptopleura ramosa (Hudson) L.Newton, 1931 (unaccepted)
  » Species Fucus epiphyllus O.F.Müller, 1777 accepted as Phycodrys rubens (Linnaeus) Batters, 1902 (unaccepted)
  » Species Fucus erica-marina S.G.Gmelin accepted as Cystoseira spinosa Sauvageau, 1912 (unaccepted, synonym)
  » Species Fucus ericifolius Turner, 1808 accepted as Caulerpa cupressoides var. ericifolia (Turner) Weber-van Bosse, 1898 (unaccepted, synonym)
  » Species Fucus ericoides Linnaeus, 1763 accepted as Ericaria selaginoides (Linnaeus) Molinari & Guiry, 2020 (unaccepted, synonym)
  » Species Fucus erinaceus Turner, 1807 accepted as Nothogenia erinacea (Turner) P.G.Parkinson, 1983 (unaccepted)
  » Species Fucus esculentus Linnaeus, 1767 accepted as Alaria esculenta (Linnaeus) Greville, 1830 (unaccepted)
  » Species Fucus evanescens C.Agardh, 1820 accepted as Fucus distichus subsp. evanescens (C.Agardh) H.T.Powell, 1957 (unaccepted)
  » Species Fucus excisus Forsskål, 1775 accepted as Fucus vesiculosus Linnaeus, 1753 (unaccepted)
  » Species Fucus excisus Linnaeus, 1753 accepted as Pelvetia canaliculata (Linnaeus) Decaisne & Thuret, 1845 (unaccepted)
  » Species Fucus fascia O.F.Müller, 1778 accepted as Petalonia fascia (O.F.Müller) Kuntze, 1898 (unaccepted)
  » Species Fucus fasciculatus Turner, 1819 accepted as Laurencia fasciculata (Turner) Greville, 1830 (unaccepted)
  » Species Fucus fasciola Roth, 1797 accepted as Dictyota fasciola (Roth) J.V.Lamouroux, 1809 (unaccepted)
  » Species Fucus fastigiatus Linnaeus, 1753 accepted as Furcellaria lumbricalis (Hudson) J.V.Lamouroux, 1813 (unaccepted, synonym)
  » Species Fucus fastigiatus J.Agardh, 1841 accepted as Silvetia compressa (J.Agardh) E.Serrão, T.O.Cho, S.M.Boo & Brawley, 1999 (unaccepted)
  » Species Fucus fibrosus Hudson, 1778 accepted as Cystoseira baccata (S.G.Gmelin) P.C.Silva, 1952 (unaccepted)
  » Species Fucus filamentosus Wulfen, 1803 accepted as Spyridia filamentosa (Wulfen) Harvey, 1833 (unaccepted)
  » Species Fucus filicinus Wulfen, 1791 accepted as Grateloupia filicina (J.V.Lamouroux) C.Agardh, 1822 (unaccepted)
  » Species Fucus filifolius C.Agardh, 1812 accepted as Sargassum filifolium (C.Agardh) C.Agardh, 1824 (unaccepted)
  » Species Fucus filiformis Strøm, 1762 accepted as Chorda filum (Linnaeus) Stackhouse, 1797 (unaccepted)
  » Species Fucus filiformis Hudson, 1762 accepted as Chondrus crispus var. filiformis (Hudson) Lyngbye, 1819 (unaccepted, synonym)
  » Species Fucus filum Linnaeus, 1753 accepted as Chorda filum (Linnaeus) Stackhouse, 1797 (unaccepted)
  » Species Fucus fimbriatus Hudson, 1778 accepted as Phyllophora pseudoceranoïdes (S.G.Gmelin) Newroth & A.R.A.Taylor ex P.S.Dixon & L.M.Irvine, 1977 (unaccepted)
  » Species Fucus fimbriatus Desfontaines, 1799 accepted as Cystoseira compressa (Esper) Gerloff & Nizamuddin, 1975 (unaccepted)
  » Species Fucus fimbriatus R.Brown ex Turner, 1811 accepted as Osmundaria fimbriata (J.V.Lamouroux) R.E.Norris, 1991 (unaccepted)
  » Species Fucus fissifolius Mertens, 1819 accepted as Sargassum fissifolium (Mertens) C.Agardh, 1823 (unaccepted, synonym)
  » Species Fucus flaccidus Labillardière, 1807 accepted as Cystophora flaccida J.Agardh, 1848 (unaccepted, synonym)
  » Species Fucus flaccidus Turner, 1807 accepted as Carpoblepharis flaccida (J.V.Lamouroux) Kützing, 1849 (unaccepted)
  » Species Fucus flagelliformis O.F.Müller, 1775 accepted as Chordaria flagelliformis (O.F.Müller) C.Agardh, 1817 (unaccepted)
  » Species Fucus flagellum S.G.Gmelin, 1768 accepted as Laminaria flagellum (S.G.Gmelin) Steudel, 1824 (unaccepted)
  » Species Fucus flavicans Mertens, 1819 accepted as Sargassum flavicans (Mertens) C.Agardh, 1820 (unaccepted)
  » Species Fucus flavus Linnaeus fil., 1782 accepted as Thaumasia flavia (Linnaeus) C.Agardh, 1824 (unaccepted)
  » Species Fucus flexuosus Esper, 1802 accepted as Carpophyllum flexuosum (Esper) Greville, 1830 (unaccepted)
  » Species Fucus floccosus Esper, 1802 accepted as Odonthalia floccosa (Esper) Falkenberg, 1901 (unaccepted)
  » Species Fucus floresii Clemente, 1807 accepted as Halymenia floresii (Clemente) C.Agardh, 1817 (unaccepted)
  » Species Fucus foeniculaceus Linnaeus, 1753 accepted as Cystoseira foeniculacea (Linnaeus) Greville, 1830 (unaccepted)
  » Species Fucus foliaceus Strøm, 1788 accepted as Palmaria palmata (Linnaeus) F.Weber & D.Mohr, 1805 (unaccepted)
  » Species Fucus foliifer Forsskål, 1775 accepted as Gracilaria foliifera (Forsskål) Børgesen, 1932 (unaccepted)
  » Species Fucus foliosissimus Lamouroux, 1813 accepted as Sargassum vulgare var. foliosissimum (J.V.Lamouroux) C.Agardh, 1820 (unaccepted, synonym)
  » Species Fucus forsskalii Mertens, 1819 accepted as Sargassum notarisii Zanardini, 1858 (unaccepted)
  » Species Fucus forsteri Mertens ex Turner, 1809 accepted as Laurencia forsteri (Mertens ex Turner) Greville, 1830 (unaccepted)
  » Species Fucus fragilis Forsskål, 1775 accepted as Actinotrichia fragilis (Forsskål) Børgesen, 1932 (unaccepted)
  » Species Fucus fraxinifolius Mertens ex Turner, 1809 accepted as Neurymenia fraxinifolia (Mertens ex Turner) J.Agardh, 1863 (unaccepted)
  » Species Fucus fruticulosus Wulfen, 1791 accepted as Vertebrata fruticulosa (Wulfen) Kuntze, 1891 (unaccepted)
  » Species Fucus fueci Bachelot de la Pylaie, 1830 accepted as Fucus distichus Linnaeus, 1767 (unaccepted)
  » Species Fucus fulvellus Turner, 1808 accepted as Sargassum fulvellum (Turner) C.Agardh, 1820 (unaccepted)
  » Species Fucus fungiformis Gunnerus, 1772 accepted as Ralfsia fungiformis (Gunnerus) Setchell & N.L.Gardner, 1924 (unaccepted)
  » Species Fucus furcatus C.Agardh, 1820 accepted as Fucus distichus Linnaeus, 1767 (unaccepted)
  » Species Fucus furcatus Esper, 1800 accepted as Fauchea repens (C.Agardh) Montagne & Bory de Saint-Vincent, 1846 (unaccepted)
  » Species Fucus furcellatus Linnaeus, 1763 accepted as Furcellaria lumbricalis (Hudson) J.V.Lamouroux, 1813 (unaccepted)
  » Species Fucus furcellatus Mohr, 1786 accepted as Polyides rotunda (Hudson) Gaillon, 1828 (unaccepted)
  » Species Fucus gaertneri S.G.Gmelin, 1768 accepted as Sporochnus anomalus (Pallas) M.J.Wynne, 2003 (unaccepted)
  » Species Fucus gardneri P.C.Silva, 1953 accepted as Fucus distichus Linnaeus, 1767 (unaccepted, synonym)
  » Species Fucus gelatinosus Desfontaines, 1799 accepted as Laurencia obtusa var. gracilis (C.Agardh) Zanardini, 1847 (unaccepted, synonym)
  » Species Fucus gelatinus Esper, 1800 accepted as Betaphycus gelatinus (Esper) Doty ex P.C.Silva, 1996 (unaccepted)
  » Species Fucus giganteus Gaudichaud, 1826 accepted as Macrocystis pyrifera (Linnaeus) C.Agardh, 1820 (unaccepted)
  » Species Fucus gigartinus Linnaeus, 1759 accepted as Gigartina pistillata (S.G.Gmelin) Stackhouse, 1809 (unaccepted)
  » Species Fucus gigartinus Oeder, 1768 accepted as Euthora cristata (C.Agardh) J.Agardh, 1847 (unaccepted)
  » Species Fucus gladiatus Labillardière, 1807 accepted as Xiphophora gladiata (Labillardière) Montagne ex Kjellman, 1893 (unaccepted)
  » Species Fucus glandulosus Solander ex Turner, 1808 accepted as Microcladia glandulosa (Solander ex Turner) Greville, 1830 (unaccepted)
  » Species Fucus gracilis Stackhouse, 1801 accepted as Gracilaria gracilis (Stackhouse) Steentoft, L.M.Irvine & Farnham, 1995 (unaccepted)
  » Species Fucus graminifolius Lepechin, 1775 accepted as Devaleraea ramentacea (Linnaeus) Guiry, 1982 (unaccepted)
  » Species Fucus graminifolius Turner, 1819 accepted as Sargassum graminifolium C.Agardh, 1820 (unaccepted)
  » Species Fucus granateus J.V.Lamouroux, 1805 accepted as Gracilaria foliifera f. granatea (J.V.Lamouroux) Børgesen, 1938 (unaccepted, synonym)
  » Species Fucus granulatus Linnaeus, 1763 accepted as Cystoseira usneoides (Linnaeus) M.Roberts, 1968 (unaccepted)
  » Species Fucus griffithsiae Turner, 1808 accepted as Gymnogongrus griffithsiae (Turner) C.Martius, 1833 (unaccepted)
  » Species Fucus gulaman M.Blanco, 1837 accepted as Gracilaria gracilis (Stackhouse) Steentoft, L.M.Irvine & Farnham, 1995 (unaccepted)
  » Species Fucus hamulosus Esper, 1800 accepted as Hypnea hamulosa (Esper) J.V.Lamouroux, 1813 (unaccepted)
  » Species Fucus harveyanus Decaisne, 1864 accepted as Hesperophycus californicus P.C.Silva, 1990 (unaccepted)
  » Species Fucus harveyanus Decaisne ex J.Agardh, 1868 accepted as Fucus ceranoides Linnaeus, 1753 (unaccepted)
  » Species Fucus helminthocorton (Schwendimann) Tourrette, 1782 accepted as Alsidium helminthochorton (Schwendimann) Kützing, 1843 (unaccepted, synonym)
  » Species Fucus hemiphyllus Turner, 1811 accepted as Sargassum hemiphyllum (Turner) C.Agardh, 1820 (unaccepted)
  » Species Fucus herbaceus Turner, 1808 accepted as Desmarestia herbacea (Turner) J.V.Lamouroux, 1813 (unaccepted)
  » Species Fucus herbaceus Hudson, 1778 accepted as Desmarestia ligulata (Stackhouse) J.V.Lamouroux, 1813 (unaccepted, synonym)
  » Species Fucus herediae Clemente, 1807 accepted as Phyllophora herediae (Clemente) J.Agardh, 1842 (unaccepted)
  » Species Fucus hetaerophyllus Clemente, 1807 accepted as Gelidium pusillum (Stackhouse) Le Jolis, 1863 (unaccepted)
  » Species Fucus heterophyllus Turner, 1808 accepted as Sargassum incisifolium (Turner) C.Agardh, 1820 (unaccepted)
  » Species Fucus hirsutus Linnaeus, 1767 accepted as Cladostephus spongiosus f. verticillatus (Lightfoot) Prud'homme van Reine, 1972 (unaccepted, synonym)
  » Species Fucus horneri Turner, 1808 accepted as Sargassum horneri (Turner) C.Agardh, 1820 (unaccepted)
  » Species Fucus hybridus A.P.de Candolle, 1805 accepted as Osmundea hybrida (A.P.de Candolle) K.W.Nam, 1994 (unaccepted)
  » Species Fucus hyperboreus Gunnerus, 1766 accepted as Laminaria hyperborea (Gunnerus) Foslie, 1884 (unaccepted)
  » Species Fucus hypnoides R.Brown ex Turner, 1809 accepted as Caulerpa flexilis J.V.Lamouroux ex C.Agardh, 1823 (unaccepted)
  » Species Fucus hypoglossoides Stackhouse, 1801 accepted as Hypoglossum hypoglossoides (Stackhouse) Collins & Hervey, 1917 (unaccepted)
  » Species Fucus hypoglossum Woodward, 1794 accepted as Hypoglossum hypoglossoides (Stackhouse) Collins & Hervey, 1917 (unaccepted)
  » Species Fucus ilicifolius Turner, 1807 accepted as Sargassum ilicifolium (Turner) C.Agardh, 1820 (unaccepted)
  » Species Fucus implexus Desfontaines, 1799 accepted as Dictyota implexa (Desfontaines) J.V.Lamouroux, 1809 (unaccepted, synonym)
  » Species Fucus incisifolius Turner, 1811 accepted as Sargassum incisifolium (Turner) C.Agardh, 1820 (unaccepted)
  » Species Fucus incurvus Hudson, 1762 accepted as Halopithys incurva (Hudson) Batters, 1902 (unaccepted)
  » Species Fucus inermis Brown ex Turner, 1811 accepted as Perithalia caudata (Labillardière) Womersley, 1967 (unaccepted, synonym)
  » Species Fucus inflatus Linnaeus, 1753 accepted as Fucus vesiculosus Linnaeus, 1753 (unaccepted, synonym)
  » Species Fucus jubatus Goodenough & Woodward, 1797 accepted as Calliblepharis jubata (Goodenough & Woodward) Kützing, 1843 (unaccepted)
  » Species Fucus kaliformis Goodenough & Woodward, 1797 accepted as Chylocladia verticillata (Lightfoot) Bliding, 1928 (unaccepted)
  » Species Fucus labillardierei Mertens ex Turner, 1809 accepted as Phacelocarpus peperocarpos (Poiret) M.J.Wynne, Ardré & P.C.Silva, 1993 (unaccepted)
  » Species Fucus lacer Wulfen, 1803 accepted as (unaccepted, synonym)
  » Species Fucus laceratus S.G.Gmelin, 1768 accepted as Cryptopleura ramosa (Hudson) L.Newton, 1931 (unaccepted, synonym)
  » Species Fucus lacerifolius Turner, 1811 accepted as Sargassum lacerifolium (Turner) C.Agardh, 1820 (unaccepted)
  » Species Fucus lacerus Stackhouse, 1797 accepted as Chondrus crispus Stackhouse, 1797 (unaccepted, synonym)
  » Species Fucus lacerus Linnaeus, 1763 accepted as Chondrus crispus Stackhouse, 1797 (unaccepted)
  » Species Fucus lacerus J.V.Lamouroux, 1813 accepted as Palmaria palmata (Linnaeus) F.Weber & D.Mohr, 1805 (unaccepted, synonym)
  » Species Fucus laciniatus Hudson, 1762 accepted as Metacallophyllis laciniata (Hudson) A.Vergés & L.Le Gall, 2017 (unaccepted)
  » Species Fucus lacinulatus M.Vahl, 1802 accepted as Gracilaria isabellana Gurgel, Fredericq & J.N.Norris, 2004 (unaccepted)
  » Species Fucus lambertii Turner, 1819 accepted as Callophyllis lambertii (Turner) Kützing, 1849 (unaccepted)
  » Species Fucus lamourouxii Turner, 1811 accepted as Caulerpa lamourouxii (Turner) C.Agardh, 1817 (unaccepted, synonym)
  » Species Fucus lanceolatus Withering, 1796 accepted as Calliblepharis jubata (Goodenough & Woodward) Kützing, 1843 (unaccepted)
  » Species Fucus langsdorfii Turner, 1811 accepted as Coccophora langsdorfii (Turner) Greville, 1830 (unaccepted)
  » Species Fucus lanosus Linnaeus, 1767 accepted as Vertebrata lanosa (Linnaeus) T.A.Christensen, 1967 (unaccepted, synonym)
  » Species Fucus larix Turner, 1819 accepted as Neorhodomela larix (Turner) Masuda, 1982 (unaccepted)
  » Species Fucus latifolius Turner, 1808 accepted as Sargassum latifolium (Turner) C.Agardh, 1820 (unaccepted)
  » Species Fucus latifolius Poiret, 1808 accepted as Sargassum ilicifolium (Turner) C.Agardh, 1820 (unaccepted)
  » Species Fucus laxus R.Brown ex Turner, 1811 accepted as Laurencia laxa (R.Brown ex Turner) Gaillon, 1828 (unaccepted)
  » Species Fucus lendigerus Linnaeus, 1753 accepted as Sargassum lendigerum (Linnaeus) C.Agardh, 1820 (unaccepted)
  » Species Fucus lichenastrum Poiret, 1817 accepted as Hydropuntia edulis (S.G.Gmelin) Gurgel & Fredericq, 2004 (unaccepted)
  » Species Fucus lichenoides Turner, 1808 accepted as Hydropuntia edulis (S.G.Gmelin) Gurgel & Fredericq, 2004 (unaccepted, synonym)
  » Species Fucus ligulatus Lightfoot, 1777 accepted as Desmarestia ligulata (Stackhouse) J.V.Lamouroux, 1813 (unaccepted, synonym)
  » Species Fucus limitaneus (Montagne) Montagne, 1856 accepted as Fucus guiryi Zardi, Nicastro, E.S.Serrão & G.A.Pearson, 2011 (unaccepted, synonym)
  » Species Fucus linariifolius Turner, 1807 accepted as Sargassum acinarium (Linnaeus) Setchell, 1933 (unaccepted)
  » Species Fucus linearifolius Turner, 1808 accepted as Sargassum linearifolium (Turner) C.Agardh, 1820 (unaccepted)
  » Species Fucus linearis Turner, 1815 accepted as Ahnfeltiopsis linearis (C.Agardh) P.C.Silva & DeCew, 1992 (unaccepted)
  » Species Fucus linearis Oeder, 1767 accepted as Fucus distichus Linnaeus, 1767 (unaccepted)
  » Species Fucus linearis Hudson, 1762 accepted as Fucus vesiculosus var. linearis (Hudson) Kützing, 1849 (unaccepted, synonym)
  » Species Fucus linearis Forsskål, 1775 accepted as Dictyota dichotoma var. intricata (C.Agardh) Greville, 1830 (unaccepted, synonym)
  » Species Fucus lineatus Turner, 1819 accepted as (unaccepted, synonym)
  » Species Fucus lingulatus Solander ex Woodward, 1794 accepted as Hypoglossum hypoglossoides (Stackhouse) Collins & Hervey, 1917 (unaccepted, synonym)
  » Species Fucus linifolius Turner, 1811 accepted as Sargassum acinarium (Linnaeus) Setchell, 1933 (unaccepted)
  » Species Fucus lividus Turner, 1819 accepted as Sarcothalia livida (Turner) Hommersand, 1993 (unaccepted)
  » Species Fucus lomation Bertoloni, 1818 accepted as Cryptonemia lomation (Bertoloni) J.Agardh, 1851 (unaccepted, synonym)
  » Species Fucus lomentarius (Lyngbye) Sommerfelt, 1826 accepted as Scytosiphon lomentaria (Lyngbye) Link, 1833 (unaccepted)
  » Species Fucus longifolius Turner, 1809 accepted as Anthophycus longifolius (Turner) Kützing, 1849 (unaccepted)
  » Species Fucus longissimus S.G.Gmelin, 1768 accepted as Gracilariopsis longissima (S.G.Gmelin) Steentoft, L.M.Irvine & Farnham, 1995 (unaccepted)
  » Species Fucus loreus Linnaeus, 1767 accepted as Himanthalia elongata (Linnaeus) S.F.Gray, 1821 (unaccepted)
  » Species Fucus lucidus R.Brown ex Turner, 1811 accepted as Pterocladia lucida (R.Brown ex Turner) J.Agardh, 1851 (unaccepted)
  » Species Fucus luetkeanus K.Mertens, 1829 accepted as Nereocystis luetkeana (K.Mertens) Postels & Ruprecht, 1840 (unaccepted)
  » Species Fucus lumbricalis Hudson, 1762 accepted as Furcellaria lumbricalis (Hudson) J.V.Lamouroux, 1813 (unaccepted, synonym)
  » Species Fucus lutarius (Chauvin ex J.Kickx f.) Kützing, 1860 accepted as Fucus spiralis var. lutarius (Kützing) Sauvageau, 1908 (unaccepted, synonym)
  » Species Fucus lycopodioides Linnaeus, 1767 accepted as Rhodomela lycopodioides (Linnaeus) C.Agardh, 1822 (unaccepted, synonym)
  » Species Fucus lycopodium Turner, 1811 accepted as Digenea simplex (Wulfen) C.Agardh, 1822 (unaccepted)
  » Species Fucus lycopodium Stackhouse, 1802 accepted as Rhodomela lycopodioides (Linnaeus) C.Agardh, 1822 (unaccepted, synonym)
  » Species Fucus mackayi Turner, 1808 accepted as Ascophyllum nodosum f. mackayi (Turner) A.C.Mathieson & Dawes, 2017 (unaccepted)
  » Species Fucus mammillosus Goodenough & Woodward, 1797 accepted as Mastocarpus stellatus (Stackhouse) Guiry, 1984 (unaccepted)
  » Species Fucus maschalocarpus Turner, 1811-1819 accepted as Carpophyllum maschalocarpum (Turner) Greville, 1830 (unaccepted)
  » Species Fucus maxillosus Poiret, 1808 accepted as Plocamium maxillosum (Poiret) J.V.Lamouroux, 1813 (unaccepted)
  » Species Fucus maximilianii Schrader, 1821 accepted as Sargassum maximilianii (Schrader) Martius, 1833 (unaccepted, synonym)
  » Species Fucus maximus Osbeck, 1757 accepted as Ecklonia maxima (Osbeck) Papenfuss, 1940 (unaccepted)
  » Species Fucus membranaceus Stackhouse, 1795 accepted as Dictyopteris polypodioides (A.P.De Candolle) J.V.Lamouroux, 1809 (unaccepted)
  » Species Fucus membranifolius Goodenough & Woodward, 1797 accepted as Phyllophora pseudoceranoïdes (S.G.Gmelin) Newroth & A.R.A.Taylor ex P.S.Dixon & L.M.Irvine, 1977 (unaccepted, synonym)
  » Species Fucus membranifolius C.Agardh, 1810 accepted as Phyllophora pseudoceranoïdes (S.G.Gmelin) Newroth & A.R.A.Taylor ex P.S.Dixon & L.M.Irvine, 1977 (unaccepted)
  » Species Fucus menziesii Turner, 1808 accepted as Egregia menziesii (Turner) Areschoug, 1876 (unaccepted)
  » Species Fucus miclonensis Bachelot de la Pylaie, 1830 accepted as Fucus distichus Linnaeus, 1767 (unaccepted)
  » Species Fucus microceratius Turner, 1809 accepted as Sargassum microceratium (Mertens ex Turner) C.Agardh, 1820 (unaccepted)
  » Species Fucus microphyllus De la Pylaie, 1829 accepted as Fucus evanescens C.Agardh, 1820 (unaccepted, synonym)
  » Species Fucus miniatus Draparnaud ex A.P.de Candolle, 1815 accepted as Wurdemannia miniata (Sprengel) Feldmann & Hamel, 1934 (unaccepted)
  » Species Fucus miniatus O.F.Müller, 1778 accepted as Metacallophyllis laciniata (Hudson) A.Vergés & L.Le Gall, 2017 (unaccepted)
  » Species Fucus minimus Hering, 1841 accepted as Chnoospora minima (Hering) Papenfuss, 1956 (unaccepted)
  » Species Fucus moniliformis Esper, 1804 accepted as Cystophora moniliformis (Esper) Womersley & Nizamuddin, 1964 (unaccepted)
  » Species Fucus moniliformis Labillardière, 1807 accepted as Hormosira banksii (Turner) Decaisne, 1842 (unaccepted)
  » Species Fucus mucronatus Turner accepted as Cystoseira nodicaulis (Withering) M.Roberts, 1967 (unaccepted)
  » Species Fucus multifidus Hudson, 1778 accepted as Osmundea osmunda (S.G.Gmelin) K.W.Nam & Maggs, 1994 (unaccepted)
  » Species Fucus multipartitus Clemente, 1807 accepted as Gracilaria multipartita (Clemente) Harvey, 1846 (unaccepted)
  » Species Fucus muricatus Turner, 1808 accepted as Cystoseira trinodis (Forsskål) C.Agardh, 1820 (unaccepted)
  » Species Fucus muricatus S.G.Gmelin, 1768 accepted as Eucheuma denticulatum (N.L.Burman) Collins & Hervey, 1917 (unaccepted)
  » Species Fucus musciformis Wulfen, 1791 accepted as Hypnea musciformis (Wulfen) J.V.Lamouroux, 1813 (unaccepted)
  » Species Fucus muscoides (A.D.Cotton) Feldmann & Magne, 1964 accepted as Fucus cottonii M.J.Wynne & Magne, 1991 (unaccepted, synonym)
  » Species Fucus muscoides Linnaeus, 1753 accepted as Acanthophora muscoides (Linnaeus) Bory de Saint-Vincent, 1828 (unaccepted)
  » Species Fucus muscoides Hudson, 1762 accepted as Desmarestia aculeata (Linnaeus) J.V.Lamouroux, 1813 (unaccepted)
  » Species Fucus muscoides Forsskål, 1775 accepted as Carradoriella elongata (Hudson) Savoie & G.W.Saunders, 2019 (unaccepted, synonym)
  » Species Fucus myagroides Mertens ex Turner, 1809 accepted as Myagropsis myagroides (Mertens ex Turner) Fensholt, 1955 (unaccepted)
  » Species Fucus myrica S.G.Gemlin, 1768 accepted as Polycladia myrica (S.G.Gmelin) Draima, Ballesteros, F.Rousseau & T.Thibaut, 2010 (unaccepted, synonym)
  » Species Fucus mytili Nienburg, 1932 accepted as Fucus vesiculosus f. mytili (Nienburg) Mathieson & Dawes, 2017 (unaccepted, synonym)
  » Species Fucus natans Linnaeus, 1753 accepted as Sargassum natans (Linnaeus) Gaillon, 1828 (unaccepted, synonym)
  » Species Fucus nayadiformis Delile, 1813 accepted as Acanthophora nayadiformis (Delile) Papenfuss, 1968 (unaccepted, synonym)
  » Species Fucus nemalion Bertoloni, 1818 accepted as Nemalion elminthoides (Velley) Batters, 1902 (unaccepted, synonym)
  » Species Fucus nervosus A.P.de Candolle, 1805 accepted as Phyllophora crispa (Hudson) P.S.Dixon, 1964 (unaccepted)
  » Species Fucus nitens N.L.Gardner, 1922 accepted as Fucus distichus Linnaeus, 1767 (unaccepted)
  » Species Fucus nodicaulis Withering, 1796 accepted as Cystoseira nodicaulis (Withering) M.Roberts, 1967 (unaccepted)
  » Species Fucus nodosus Linnaeus, 1753 accepted as Ascophyllum nodosum (Linnaeus) Le Jolis, 1863 (unaccepted, synonym)
  » Species Fucus nodularius Mertens, 1819 accepted as Hormophysa cuneiformis (J.F.Gmelin) P.C.Silva, 1987 (unaccepted)
  » Species Fucus nootkanus Esper, 1802 accepted as Hypnea nidifica J.Agardh, 1852 (unaccepted)
  » Species Fucus norvegicus Gunnerus, 1772 accepted as Chondrus crispus Stackhouse, 1797 (unaccepted)
  » Species Fucus obtusatus Labillardière, 1807 accepted as Melanthalia obtusata (Labillardière) J.Agardh, 1852 (unaccepted)
  » Species Fucus obtusus Hudson, 1778 accepted as Laurencia obtusa (Hudson) J.V.Lamouroux, 1813 (unaccepted)
  » Species Fucus ocellatus J.V.Lamouroux, 1802 accepted as Nitophyllum punctatum (Stackhouse) Greville, 1830 (unaccepted)
  » Species Fucus oederi Gunnerus, 1772 accepted as Osmundea oederi (Gunnerus) G.Furnari, 2008 (unaccepted)
  » Species Fucus oederi Esper, 1802 accepted as Gigartina pistillata (S.G.Gmelin) Stackhouse, 1809 (unaccepted, synonym)
  » Species Fucus onustus Mertens, 1819 accepted as Sirophysalis trinodis (Forsskal) Kützing, 1849 (unaccepted)
  » Species Fucus opuntia Goodenough & Woodward, 1797 accepted as Catenella caespitosa (Withering) L.M.Irvine, 1976 (unaccepted)
  » Species Fucus ornatus Linnaeus, 1771 accepted as Suhria vittata (Linnaeus) Endlicher, 1843 (unaccepted)
  » Species Fucus osmunda S.G.Gmelin, 1768 accepted as Osmundea osmunda (S.G.Gmelin) K.W.Nam & Maggs, 1994 (unaccepted)
  » Species Fucus osmundaceus Turner, 1809 accepted as Stephanocystis osmundacea (Turner) Trevisan, 1843 (unaccepted, synonym)
  » Species Fucus osmundus S.G.Gmelin, 1768 accepted as Osmundea osmunda (S.G.Gmelin) K.W.Nam & Maggs, 1994 (unaccepted)
  » Species Fucus ovalis Hudson, 1778 accepted as Gastroclonium ovatum (Hudson) Papenfuss, 1944 (unaccepted)
  » Species Fucus ovatus Hudson, 1762 accepted as Gastroclonium ovatum (Hudson) Papenfuss, 1944 (unaccepted)
  » Species Fucus ovinus Gunnerus, 1766 accepted as Palmaria palmata (Linnaeus) F.Weber & D.Mohr, 1805 (unaccepted)
  » Species Fucus pallidus Turner, 1808 accepted as Sargassum pallidum (Turner) C.Agardh, 1820 (unaccepted)
  » Species Fucus palmatus Linnaeus, 1753 accepted as Palmaria palmata (Linnaeus) F.Weber & D.Mohr, 1805 (unaccepted, synonym)
  » Species Fucus palmetta Stackhouse, 1801 accepted as Rhodymenia pseudopalmata (J.V.Lamouroux) P.C.Silva, 1952 (unaccepted, synonym)
  » Species Fucus paniculatus Turner, 1811 accepted as Acrocarpia paniculata (Turner) Areschoug, 1854 (unaccepted)
  » Species Fucus papillosus Forsskål, 1775 accepted as Palisada perforata (Bory) K.W.Nam, 2007 (unaccepted)
  » Species Fucus paradoxus R.Brown ex Turner, 1811 accepted as Sargassum paradoxum (R.Brown ex Turner) Gaillon, 1828 (unaccepted)
  » Species Fucus parvifolius Turner, 1811 accepted as Sargassum parvifolium (Turner) C.Agardh, 1820 (unaccepted)
  » Species Fucus patens C.Agardh, 1815 accepted as Sargassum patens C.Agardh, 1820 (unaccepted)
  » Species Fucus patens Goodenough & Woodward, 1797 accepted as Chondrus crispus Stackhouse, 1797 (unaccepted)
  » Species Fucus pavonicus Linnaeus, 1753 accepted as Padina pavonica (Linnaeus) Thivy, 1960 (unaccepted, synonym)
  » Species Fucus pavonius Linnaeus, 1759 accepted as Padina pavonica (Linnaeus) Thivy, 1960 (unaccepted)
  » Species Fucus pectinatus Gunnerus, 1772 accepted as Ptilota serrata Kützing, 1847 (unaccepted)
  » Species Fucus pedunculatus Hudson, 1778 accepted as Sporochnus pedunculatus (Hudson) C.Agardh, 1817 (unaccepted)
  » Species Fucus peniculus R.Brown ex Turner, 1819 accepted as Acetabularia peniculus (R.Brown ex Turner) Solms-Laubach, 1895 (unaccepted)
  » Species Fucus peperocarpos Poiret, 1808 accepted as Phacelocarpus peperocarpos (Poiret) M.J.Wynne, Ardré & P.C.Silva, 1993 (unaccepted)
  » Species Fucus perforatus Bory de Saint-Vincent, 1803 accepted as Palisada perforata (Bory) K.W.Nam, 2007 (unaccepted, synonym)
  » Species Fucus peronii Mertens, 1819 accepted as Sargassum peronii C.Agardh, 1820 (unaccepted)
  » Species Fucus pertusus K.H.Mertens, 1829 accepted as Agarum pertusum (K.H.Mertens) Postels & Ruprecht, 1840 (unaccepted, synonym)
  » Species Fucus phenax Sprengel, 1809 accepted as Rytiphlaea tinctoria (Clemente) C.Agardh, 1824 (unaccepted, synonym)
  » Species Fucus phyllanthus Turner, 1819 accepted as Carpophyllum flexuosum (Esper) Greville, 1830 (unaccepted, synonym)
  » Species Fucus phyllitis Stackhouse, 1796 accepted as Saccharina latissima (Linnaeus) C.E.Lane, C.Mayes, Druehl & G.W.Saunders, 2006 (unaccepted)
  » Species Fucus pilularia S.G.Gmelin, 1768 accepted as Bonnemaisonia pilularia (S.G.Gmelin) C.Agardh, 1822 (unaccepted, synonym)
  » Species Fucus pilulifer Turner, 1808 accepted as Sargassum piluliferum (Turner) C.Agardh, 1820 (unaccepted)
  » Species Fucus pinastroides S.G.Gmelin, 1768 accepted as Halopithys incurva (Hudson) Batters, 1902 (unaccepted, synonym)
  » Species Fucus pinnatifidus Hudson, 1762 accepted as Osmundea pinnatifida (Hudson) Stackhouse, 1809 (unaccepted, synonym)
  » Species Fucus pinnatifidus Strøm, 1788 accepted as Osmundea ramosissima Athanasiadis, 1996 (unaccepted)
  » Species Fucus pinnatifidus Hornemann, 1813 accepted as Osmundea ramosissima Athanasiadis, 1996 (unaccepted)
  » Species Fucus pinnatifidus Oeder, 1767 accepted as Odonthalia dentata (Linnaeus) Lyngbye, 1819 (unaccepted)
  » Species Fucus pinnatifolius C.Agardh, 1815 accepted as Sargassum piluliferum (Turner) C.Agardh, 1820 (unaccepted, synonym)
  » Species Fucus pinnatus Linnaeus f., 1782 accepted as Caulerpa pinnata C.Agardh, 1817 (unaccepted)
  » Species Fucus pinnatus Gunnerus, 1766 accepted as Alaria esculenta (Linnaeus) Greville, 1830 (unaccepted)
  » Species Fucus pinnatus Hudson, 1762 accepted as Pterocladiella capillacea (S.G.Gmelin) Santelices & Hommersand, 1997 (unaccepted)
  » Species Fucus pistillatus S.G.Gmelin, 1768 accepted as Gigartina pistillata (S.G.Gmelin) Stackhouse, 1809 (unaccepted)
  » Species Fucus platycarpus Turner, 1809 accepted as Botryoglossum platycarpum (Turner) Kützing, 1843 (unaccepted)
  » Species Fucus platycarpus Thuret, 1851 accepted as Fucus guiryi Zardi, Nicastro, E.S.Serrão & G.A.Pearson, 2011 (unaccepted, illegitimate name (later homonym))
  » Species Fucus platylobium Mertens, 1819 accepted as Cystophora platylobium (Mertens) J.Agardh, 1848 (unaccepted)
  » Species Fucus plicatus Hudson, 1762 accepted as Ahnfeltia plicata (Hudson) Fries, 1836 (unaccepted, synonym)
  » Species Fucus plicatus Esper, 1798 accepted as Ahnfeltia plicata (Hudson) Fries, 1836 (unaccepted)
  » Species Fucus plocamium S.G.Gmelin, 1768 accepted as Plocamium cartilagineum (Linnaeus) P.S.Dixon, 1967 (unaccepted)
  » Species Fucus plumaris Forsskål, 1775 accepted as Caulerpa sertularioides (S.G.Gmelin) M.Howe, 1905 (unaccepted)
  » Species Fucus plumosus Hudson, 1762 accepted as Plumaria plumosa (Hudson) Kuntze, 1891 (unaccepted)
  » Species Fucus plumosus Linnaeus, 1767 accepted as Ptilota gunneri P.C.Silva, Maggs & L.M.Irvine, 1993 (unaccepted)
  » Species Fucus poiteaui J.V.Lamouroux, 1805 accepted as Yuzurua poiteaui (J.V.Lamouroux) Martin-Lescanne, 2010 (unaccepted)
  » Species Fucus polypodioides Desfontaines, 1799 accepted as Dictyopteris polypodioides (A.P.De Candolle) J.V.Lamouroux, 1809 (unaccepted)
  » Species Fucus polypodioides S.G.Gmelin, 1768 accepted as Gastroclonium ovatum (Hudson) Papenfuss, 1944 (unaccepted)
  » Species Fucus polyschides Lightfoot, 1777 accepted as Saccorhiza polyschides (Lightfoot) Batters, 1902 (unaccepted)
  » Species Fucus potatorum Labillardière, 1807 accepted as Durvillaea potatorum (Labillardière) Areschoug, 1854 (unaccepted)
  » Species Fucus pristoides Turner, 1807 accepted as Gelidium pristoides (Turner) Kützing, 1843 (unaccepted)
  » Species Fucus procerrimus Esper, 1800 accepted as Gracilaria gracilis (Stackhouse) Steentoft, L.M.Irvine & Farnham, 1995 (unaccepted)
  » Species Fucus prolifer M.Blanco, 1837 accepted as Halimeda opuntia (Linnaeus) J.V.Lamouroux, 1816 (unaccepted)
  » Species Fucus prolifer Lightfoot, 1777 accepted as Phyllophora crispa (Hudson) P.S.Dixon, 1964 (unaccepted, synonym)
  » Species Fucus prolifer Forsskål, 1775 accepted as Caulerpa prolifera (Forsskål) J.V.Lamouroux, 1809 (unaccepted)
  » Species Fucus pruniformis Gunnerus, 1772 accepted as Himanthalia elongata (Linnaeus) S.F.Gray, 1821 (unaccepted)
  » Species Fucus pseudoceranoïdes S.G.Gmelin, 1768 accepted as Phyllophora pseudoceranoïdes (S.G.Gmelin) Newroth & A.R.A.Taylor ex P.S.Dixon & L.M.Irvine, 1977 (unaccepted)
  » Species Fucus pseudociliatus J.V.Lamouroux accepted as Taonia pseudociliata (J.V.Lamouroux) Nizamuddin & Godeh, 1993 (unaccepted)
  » Species Fucus pseudocrispus Clemente, 1807 accepted as Scinaia furcellata (Turner) J.Agardh, 1851 (unaccepted)
  » Species Fucus pseudopalmatus J.V.Lamouroux, 1805 accepted as Rhodymenia pseudopalmata (J.V.Lamouroux) P.C.Silva, 1952 (unaccepted)
  » Species Fucus ptilotus Gunnerus, 1772 accepted as Ptilota gunneri P.C.Silva, Maggs & L.M.Irvine, 1993 (unaccepted)
  » Species Fucus pumilus Vahl, 1792 accepted as Fimbrifolium dichotomum (Lepechin) G.I.Hansen, 1980 (unaccepted)
  » Species Fucus punctatus Stackhouse, 1796 accepted as Nitophyllum punctatum (Stackhouse) Greville, 1830 (unaccepted)
  » Species Fucus purpurascens Hudson, 1778 accepted as Cystoclonium purpureum (Hudson) Batters, 1902 (unaccepted, synonym)
  » Species Fucus purpureus Hudson, 1762 accepted as Cystoclonium purpureum (Hudson) Batters, 1902 (unaccepted)
  » Species Fucus purpureus Turner, 1807-1808 accepted as Rytiphlaea tinctoria (Clemente) C.Agardh, 1824 (unaccepted, synonym)
  » Species Fucus pusillus Stackhouse, 1795 accepted as Gelidium pusillum (Stackhouse) Le Jolis, 1863 (unaccepted)
  » Species Fucus pygmaeus Lightfoot, 1777 accepted as Lichina pygmaea (Lightf.) C. Agardh, 1817 (unaccepted)
  » Species Fucus pyrifer Linnaeus, 1771 accepted as Macrocystis pyrifera (Linnaeus) C.Agardh, 1820 (unaccepted)
  » Species Fucus quercifolius R.Brown ex Turner, 1809 accepted as Platythalia quercifolia (R.Brown ex Turner) Sonder, 1848 (unaccepted)
  » Species Fucus racemosus Forsskål, 1775 accepted as Caulerpa racemosa (Forsskål) J.Agardh, 1873 (unaccepted)
  » Species Fucus radiatus Goodenough & Woodward, 1797 accepted as Polyides rotunda (Hudson) Gaillon, 1828 (unaccepted)
  » Species Fucus radiatus Turner, 1808 accepted as Ecklonia radiata (C.Agardh) J.Agardh, 1848 (unaccepted)
  » Species Fucus radiciformis R.Brown ex Turner, 1809 accepted as Sporochnus radiciformis (R.Brown ex Turner) C.Agardh, 1817 (unaccepted)
  » Species Fucus radula Esper, 1802 accepted as Sarcothalia radula (Esper) Edyvane & Womersley, 1994 (unaccepted)
  » Species Fucus ramentaceus Linnaeus, 1767 accepted as Devaleraea ramentacea (Linnaeus) Guiry, 1982 (unaccepted)
  » Species Fucus ramosissimus Oeder, 1766 accepted as Osmundea oederi (Gunnerus) G.Furnari, 2008 (unaccepted, synonym)
  » Species Fucus rangiferina R.Brown ex Turner, 1811 accepted as Callophyllis rangiferina (R.Brown ex Turner) Womersley, 1973 (unaccepted)
  » Species Fucus reniformis Turner, 1809 accepted as Kallymenia reniformis (Turner) J.Agardh, 1842 (unaccepted)
  » Species Fucus repens Lightfoot, 1777 accepted as Catenella caespitosa (Withering) L.M.Irvine, 1976 (unaccepted, synonym)
  » Species Fucus retortus Mertens, 1819 accepted as Cystophora retorta (Mertens) J.Agardh, 1848 (unaccepted)
  » Species Fucus retroflexus Labillardière, 1807 accepted as Cystophora retroflexa (Labillardière) J.Agardh, 1848 (unaccepted)
  » Species Fucus rhizodes Ehrhart ex Turner, 1819 accepted as Stilophora tenella (Esper) P.C.Silva, 1996 (unaccepted)
  » Species Fucus rigidus Vahl, 1802 accepted as Gelidiella acerosa (Forsskål) Feldmann & Hamel, 1934 (unaccepted)
  » Species Fucus rosa-marina S.G.Gmelin, 1768 accepted as Constantinea rosa-marina (S.G.Gmelin) Postels & Ruprecht, 1840 (unaccepted)
  » Species Fucus roseus O.F.Müller, 1775 accepted as Phycodrys rubens (Linnaeus) Batters, 1902 (unaccepted)
  » Species Fucus rotundatus Hudson, 1762 accepted as Bifurcaria bifurcata R.Ross, 1958 (unaccepted)
  » Species Fucus rotundifolius Draparnaud, 1815 accepted as Kallymenia reniformis (Turner) J.Agardh, 1842 (unaccepted, synonym)
  » Species Fucus rotundus Hudson, 1762 accepted as Polyides rotunda (Hudson) Gaillon, 1828 (unaccepted)
  » Species Fucus rubens Linnaeus, 1753 accepted as Phycodrys rubens (Linnaeus) Batters, 1902 (unaccepted, synonym)
  » Species Fucus rubens Esper, 1799 accepted as Palmaria palmata (Linnaeus) F.Weber & D.Mohr, 1805 (unaccepted)
  » Species Fucus rubescens Sommerfelt, 1826 accepted as Palmaria palmata (Linnaeus) F.Weber & D.Mohr, 1805 (unaccepted)
  » Species Fucus ruscifolius Turner, 1802 accepted as Apoglossum ruscifolium (Turner) J.Agardh, 1898 (unaccepted, synonym)
  » Species Fucus saccatus Lepechin, 1775 accepted as Halosaccion saccatum (Lepechin) Kützing, 1866 (unaccepted)
  » Species Fucus saccharinus Linnaeus, 1753 accepted as Saccharina latissima (Linnaeus) C.E.Lane, C.Mayes, Druehl & G.W.Saunders, 2006 (unaccepted)
  » Species Fucus salicifolius S.G.Gmelin, 1768 accepted as Sargassum vulgare C.Agardh, 1820 (unaccepted)
  » Species Fucus saltii Turner, 1819 accepted as Sargassum saltii (Turner) C.Agardh, 1824 (unaccepted)
  » Species Fucus sanguineus Hudson, 1762 accepted as Delesseria sanguinea (Hudson) J.V.Lamouroux, 1813 (unaccepted)
  » Species Fucus sargasso S.G.Gmelin, 1768 accepted as Sargassum natans (Linnaeus) Gaillon, 1828 (unaccepted)
  » Species Fucus sarniensis Mertens in Roth, 1806 accepted as Palmaria palmata (Linnaeus) F.Weber & D.Mohr, 1805 (unaccepted)
  » Species Fucus scalpelliformis R.Brown ex Turner, 1809 accepted as Caulerpa scalpelliformis (R.Brown ex Turner) C.Agardh, 1817 (unaccepted)
  » Species Fucus scoparius Mertens ex Turner, 1809 accepted as Sargassum siliquastrum (Mertens ex Turner) C.Agardh, 1820 (unaccepted)
  » Species Fucus scoparius Strøm, 1762 accepted as Laminaria hyperborea (Gunnerus) Foslie, 1884 (unaccepted, synonym)
  » Species Fucus scorpioides Hudson, 1762 accepted as Bostrychia scorpioides (Hudson) Montagne, 1842 (unaccepted)
  » Species Fucus scorpioides O.F.Müller, 1782 accepted as Cystoclonium purpureum (Hudson) Batters, 1902 (unaccepted)
  » Species Fucus scorpioides Hornemann, 1813 accepted as Ascophyllum nodosum f. scorpioides Hauck, 1883 (unaccepted)
  » Species Fucus seaforthii Turner, 1808 accepted as Alsidium seaforthii (Turner) J.Agardh, 1841 (unaccepted)
  » Species Fucus sedoides Desfontaines, 1799 accepted as Cystoseira sedoides (Desfontaines) C.Agardh, 1820 (unaccepted)
  » Species Fucus sedoides R.Brown ex Turner, 1809 accepted as Caulerpa sedoides C.Agardh, 1817 (unaccepted)
  » Species Fucus selaginoides Linnaeus, 1759 accepted as Ericaria selaginoides (Linnaeus) Molinari & Guiry, 2020 (unaccepted)
  » Species Fucus selago Turner, 1808 accepted as Caulerpa selago (Turner) C.Agardh, 1817 (unaccepted)
  » Species Fucus sericeus S.G.Gmelin, 1768 accepted as Plumaria sericea (S.G.Gmelin) Ruprecht, 1850 (unaccepted)
  » Species Fucus serra S.G.Gmelin, 1768 accepted as Gelidium bipectinatum G.Furnari, 1999 (unaccepted)
  » Species Fucus serratifolius C.Agardh, 1815 accepted as Sargassum serratifolium (C.Agardh) C.Agardh, 1820 (unaccepted)
  » Species Fucus serratifolius Thunberg, 1815 accepted as Sargassum siliquastrum (Mertens ex Turner) C.Agardh, 1820 (unaccepted)
  » Species Fucus serrulatus Forsskål, 1775 accepted as Caulerpa serrulata (Forsskål) J.Agardh, 1837 (unaccepted)
  » Species Fucus sertolara Bertoloni, 1819 accepted as Halimeda sertolara (Bertoloni) Zanardini, 1840 (unaccepted, synonym)
  » Species Fucus sertularioides S.G.Gmelin, 1768 accepted as Caulerpa sertularioides (S.G.Gmelin) M.Howe, 1905 (unaccepted)
  » Species Fucus siliculosus Stackhouse, 1796 accepted as Halidrys siliquosa (Linnaeus) Lyngbye, 1819 (unaccepted)
  » Species Fucus siliquastrus Mertens ex Turner, 1809 accepted as Sargassum siliquastrum (Mertens ex Turner) C.Agardh, 1820 (unaccepted)
  » Species Fucus siliquosus Linnaeus, 1753 accepted as Halidrys siliquosa (Linnaeus) Lyngbye, 1819 (unaccepted)
  » Species Fucus simpliciuscula R.Brown ex Turner, 1809 accepted as Caulerpa simpliciuscula (R.Brown ex Turner) C.Agardh, 1823 (unaccepted)
  » Species Fucus sinuosus Goodenough & Woodward, 1797 accepted as Phycodrys rubens (Linnaeus) Batters, 1902 (unaccepted)
  » Species Fucus sisymbryoides Turner, 1809 accepted as Myagropsis myagroides (Mertens ex Turner) Fensholt, 1955 (unaccepted)
  » Species Fucus soboliferus M.Vahl, 1792 accepted as Palmaria palmata (Linnaeus) F.Weber & D.Mohr, 1805 (unaccepted)
  » Species Fucus spartioides Turner, 1819 accepted as Cystophora moniliformis (Esper) Womersley & Nizamuddin, 1964 (unaccepted)
  » Species Fucus spiciferus M.Vahl, 1802 accepted as Acanthophora spicifera (M.Vahl) Børgesen, 1910 (unaccepted)
  » Species Fucus spiniformis J.V.Lamouroux, 1805 accepted as Gelidiella acerosa (Forsskål) Feldmann & Hamel, 1934 (unaccepted)
  » Species Fucus spinosus Linnaeus, 1771 accepted as Eucheuma denticulatum (N.L.Burman) Collins & Hervey, 1917 (unaccepted)
  » Species Fucus spinosus S.G.Gmelin, 1768 accepted as Gelidium spinosum (S.G.Gmelin) P.C.Silva, 1996 (unaccepted)
  » Species Fucus squamarius S.G.Gmelin, 1768 accepted as Peyssonnelia squamaria (S.G.Gmelin) Decaisne ex J.Agardh, 1842 (unaccepted)
  » Species Fucus stackhousei Clemente, 1807 accepted as Helminthocladia stackhousei (Clemente) J.Cremades, 1993 (unaccepted)
  » Species Fucus stellatus Stackhouse, 1796 accepted as Mastocarpus stellatus (Stackhouse) Guiry, 1984 (unaccepted)
  » Species Fucus stiriata Turner, 1807 accepted as Sarcothalia stiriata (Turner) Leister, 1993 (unaccepted)
  » Species Fucus stiriatus Turner, 1808 accepted as Sarcothalia stiriata (Turner) Leister, 1993 (unaccepted)
  » Species Fucus striatus Draparnaud, 1824 accepted as Rytiphlaea tinctoria (Clemente) C.Agardh, 1824 (unaccepted, synonym)
  » Species Fucus subfarcinatus Mertens, 1819 accepted as Cystophora subfarcinata (Mertens) J.Agardh, 1848 (unaccepted)
  » Species Fucus subfuscus Woodward, 1791 accepted as Rhodomela confervoides (Hudson) P.C.Silva, 1952 (unaccepted)
  » Species Fucus subrepandus Forsskål, 1775 accepted as Sargassum subrepandum (Forsskål) C.Agardh, 1820 (unaccepted)
  » Species Fucus swartzii C.Agardh, 1815 accepted as Sargassum thunbergii (Mertens ex Roth) Kuntze, 1880 (unaccepted)
  » Species Fucus swartzii Turner, 1811 accepted as Sargassum swartzii C.Agardh, 1820 (unaccepted)
  » Species Fucus tamariscifolius Hudson, 1762 accepted as Ericaria selaginoides (Linnaeus) Molinari & Guiry, 2020 (unaccepted)
  » Species Fucus taxifolius M.Vahl, 1802 accepted as Caulerpa taxifolia (M.Vahl) C.Agardh, 1817 (unaccepted)
  » Species Fucus taxiformis Delile, 1813 accepted as Asparagopsis taxiformis (Delile) Trevisan de Saint-Léon, 1845 (unaccepted)
  » Species Fucus telephifolius Turner, 1808 accepted as Sargassum telephifolium (Turner) C.Agardh, 1820 (unaccepted)
  » Species Fucus tenax Turner, 1806 accepted as Gloiopeltis tenax (Turner) Decaisne, 1842 (unaccepted)
  » Species Fucus tenellus Esper, 1800 accepted as Stilophora tenella (Esper) P.C.Silva, 1996 (unaccepted)
  » Species Fucus tenellus M.Vahl, 1802 accepted as Bostrychia tenella (J.V.Lamouroux) J.Agardh, 1863 (unaccepted)
  » Species Fucus tenerrimus Esper, 1800 accepted as Lomentaria tenerrima (Esper) P.C.Silva, 1996 (unaccepted)
  » Species Fucus tenerrimus Clemente, 1807 accepted as Palisada tenerrima (Cremades) D.Serio, M.Cormaci, G.Furnari & F.Boisset, 2010 (unaccepted)
  » Species Fucus tentaculatus Bertoloni, 1818 accepted as Gymnogongrus griffithsiae (Turner) C.Martius, 1833 (unaccepted, synonym)
  » Species Fucus tenuissimus Withering, 1796 accepted as Chondria capillaris (Hudson) M.J.Wynne, 1991 (unaccepted)
  » Species Fucus teres Goodenough & Woodward, 1797 accepted as Alaria esculenta (Linnaeus) Greville, 1830 (unaccepted)
  » Species Fucus tetragonus Delile, 1813 accepted as Sargassum dentifolium (Turner) C.Agardh, 1820 (unaccepted, synonym)
  » Species Fucus textilis Clemente, 1807 accepted as Codium textile (Clemente) C.Agardh, 1817 (unaccepted)
  » Species Fucus thunbergii Mertens ex Roth, 1800 accepted as Sargassum thunbergii (Mertens ex Roth) Kuntze, 1880 (unaccepted, synonym)
  » Species Fucus thyrsoides Turner, 1808 accepted as Laurencia thyrsoides (Turner) Gaillon, 1828 (unaccepted)
  » Species Fucus tilesii C.Agardh, 1812 accepted as Coccophora langsdorfii (Turner) Greville, 1830 (unaccepted)
  » Species Fucus tinctorius Clemente, 1807 accepted as Rytiphlaea tinctoria (Clemente) C.Agardh, 1824 (unaccepted)
  » Species Fucus tomentosus Hudson, 1778 accepted as Codium tomentosum Stackhouse, 1797 (unaccepted)
  » Species Fucus tortilis C.Agardh, 1812 accepted as Sargassum siliquastrum (Mertens ex Turner) C.Agardh, 1820 (unaccepted)
  » Species Fucus torulosus R.Brown ex Turner, 1811 accepted as Cystophora torulosa (R.Brown ex Turner) J.Agardh, 1848 (unaccepted)
  » Species Fucus tournefortii J.V.Lamouroux, 1805 accepted as Zonaria tournefortii (J.V.Lamouroux) Montagne, 1846 (unaccepted)
  » Species Fucus triangularis J.F.Gmelin, 1792 accepted as Alsidium triquetrum (S.G.Gmelin) Trevisan, 1845 (unaccepted)
  » Species Fucus tridens Mertens ex Turner, 1811 accepted as Dictyomenia tridens (Mertens ex Turner) Greville, 1830 (unaccepted)
  » Species Fucus trigonus Clemente, 1807 accepted as Scinaia furcellata (Turner) J.Agardh, 1851 (unaccepted)
  » Species Fucus trinodis Forsskål, 1775 accepted as Sirophysalis trinodis (Forsskal) Kützing, 1849 (unaccepted, synonym)
  » Species Fucus triqueter Linnaeus, 1771 accepted as Hormophysa cuneiformis (J.F.Gmelin) P.C.Silva, 1987 (unaccepted)
  » Species Fucus triqueter S.G.Gmelin, 1768 accepted as Alsidium triquetrum (S.G.Gmelin) Trevisan, 1845 (unaccepted)
  » Species Fucus truncatus Pallas, 1776 accepted as Coccotylus truncatus (Pallas) M.J.Wynne & J.N.Heine, 1992 (unaccepted)
  » Species Fucus tuberculatus Hudson, 1778 accepted as Bifurcaria bifurcata R.Ross, 1958 (unaccepted)
  » Species Fucus tuberculatus Solander, 1777 accepted as Cystoclonium purpureum (Hudson) Batters, 1902 (unaccepted, synonym)
  » Species Fucus tubulosus Lepechin, 1775 accepted as Devaleraea ramentacea (Linnaeus) Guiry, 1982 (unaccepted)
  » Species Fucus tuniformis Bertoloni, 1819 accepted as Cryptonemia tuniformis (Bertoloni) Zanardini, 1868 (unaccepted)
  » Species Fucus turbinatus Linnaeus, 1753 accepted as Turbinaria turbinata (Linnaeus) Kuntze, 1898 (unaccepted)
  » Species Fucus usnea R.Brown ex Turner, 1811 accepted as Hymenocladia usnea (R.Brown ex Turner) J.Agardh, 1852 (unaccepted)
  » Species Fucus usneoides Linnaeus, 1759 accepted as Cystoseira usneoides (Linnaeus) M.Roberts, 1968 (unaccepted)
  » Species Fucus uvarius J.A.Murray, 1774 accepted as Botryocladia botryoides (Wulfen) Feldmann, 1941 (unaccepted, synonym)
  » Species Fucus uvifer Turner, 1811 accepted as Caulerpa racemosa (Forsskål) J.Agardh, 1873 (unaccepted)
  » Species Fucus uvifer Forsskål, 1775 accepted as Laurencia uvifera (Forsskål) Børgesen, 1932 (unaccepted)
  » Species Fucus valentiae Turner, 1809 accepted as Hypnea valentiae (Turner) Montagne, 1841 (unaccepted)
  » Species Fucus variabilis Goodenough & Woodward, 1797 accepted as Rhodomela confervoides (Hudson) P.C.Silva, 1952 (unaccepted)
  » Species Fucus venosus Linnaeus, 1771 accepted as Hymenena venosa (Linnaeus) C.Krauss, 1846 (unaccepted)
  » Species Fucus vermicularis Turner, 1815 accepted as Ahnfeltiopsis vermicularis (C.Agardh) P.C.Silva & DeCew, 1992 (unaccepted)
  » Species Fucus vermicularis (Scopoli) Bertoloni, 1819 accepted as Dasycladus vermicularis (Scopoli) Krasser, 1898 (unaccepted)
  » Species Fucus verrucosus Hudson, 1762 accepted as Gracilariopsis longissima (S.G.Gmelin) Steentoft, L.M.Irvine & Farnham, 1995 (unaccepted, synonym)
  » Species Fucus verruculosus Bertoloni, 1818 accepted as Rissoella verruculosa (Bertoloni) J.Agardh, 1851 (unaccepted)
  » Species Fucus verruculosus Mertens, 1819 accepted as Phyllotricha verruculosa (C.Agardh) R.R.M.Dixon & Huisman, 2012 (unaccepted)
  » Species Fucus versicolor S.G.Gmelin, 1768 accepted as Gelidium versicolor (S.G.Gmelin) J.V.Lamouroux, 1813 (unaccepted)
  » Species Fucus verticillatus Lightfoot, 1777 accepted as Chylocladia verticillata (Lightfoot) Bliding, 1928 (unaccepted)
  » Species Fucus vestitus R.Brown ex Turner, 1811 accepted as Sargassum vestitum (R.Brown ex Turner) C.Agardh, 1820 (unaccepted)
  » Species Fucus virgatus Mertens, 1819 accepted as Sargassum virgatum C.Agardh, 1820 (unaccepted)
  » Species Fucus virgatus Gunnerus, 1766 accepted as Desmarestia aculeata (Linnaeus) J.V.Lamouroux, 1813 (unaccepted)
  » Species Fucus viridis O.F.Müller, 1782 accepted as Desmarestia viridis (O.F.Müller) J.V.Lamouroux, 1813 (unaccepted)
  » Species Fucus viscidus Forsskål, 1775 accepted as Liagora viscida (Forsskål) C.Agardh, 1822 (unaccepted)
  » Species Fucus vitifolius Bonpland, 1809 accepted as Caulerpa vitifolia (Bonpland) J.V.Lamouroux (unaccepted, synonym)
  » Species Fucus vittatus Linnaeus, 1767 accepted as Gelidium vittatum (Linnaeus) Kützing, 1843 (unaccepted)
  » Species Fucus volubilis Linnaeus, 1759 accepted as Osmundaria volubilis (Linnaeus) R.E.Norris, 1991 (unaccepted, synonym)
  » Species Fucus wiggii Turner, 1802 accepted as Naccaria wiggii (Turner) Endlicher ex J.Agardh, 1842 (unaccepted)
  » Species Fucus woodwardia R.Brown ex Turner, 1811 accepted as Dictyopteris woodwardia (R.Brown ex Turner) C.Agardh, 1817 (unaccepted)
  » Species Fucus wrightii Harvey, 1860 accepted as Silvetia babingtonii (Harvey) E.A.Serrão, T.O.Cho, S.M.Boo & Brawley, 1999 (unaccepted)
  » Species Fucus wrightii Turner, 1811 accepted as Gracilaria wrightii (Turner) J.Agardh, 1852 (unaccepted, synonym)
  » Species Fucus zonalis J.V.Lamouroux, 1805 accepted as Stypopodium zonale (J.V.Lamouroux) Papenfuss, 1940 (unaccepted)
  » Species Fucus zosteroides J.V.Lamouroux, 1805 accepted as Dictyota dichotoma (Hudson) J.V.Lamouroux, 1809 (unaccepted, synonym)
  » Species Fucus zosteroides Turner, 1819 accepted as Ericaria zosteroides (C.Agardh) Molinari & Guiry, 2020 (unaccepted)
  » Species Fucus acutus 'Turner' (uncertain)
  » Species Fucus albus Esper, 1798 (uncertain)
  » Species Fucus allantoides Brown ex Turner, 1819 (uncertain)
  » Species Fucus angulatus S.G.Gmelin, 1768 (uncertain)
  » Species Fucus angulatus Roussel, 1806 (uncertain)
  » Species Fucus articulatus S.G.Gmelin, 1768 (uncertain)
  » Species Fucus atomarius S.G.Gmelin, 1768 (uncertain)
  » Species Fucus barbulatus Poiret (uncertain)
  » Species Fucus bastera S.G.Gmelin, 1768 (uncertain)
  » Species Fucus bicornis Gmelin (uncertain)
  » Species Fucus bicornis De la Pylaie (uncertain)
  » Species Fucus bipinnatus Desfontaines, 1799 (uncertain)
  » Species Fucus brevifolius Poiret (uncertain)
  » Species Fucus buxbaumii C.Agardh (uncertain)
  » Species Fucus callopilophorus Forsskål, 1775 (uncertain)
  » Species Fucus capensis Areschoug, 1860 (uncertain)
  » Species Fucus cartilagineus Gunnerus, 1772 (uncertain)
  » Species Fucus caulescens Gmelin (uncertain)
  » Species Fucus cirrhifolius West (uncertain)
  » Species Fucus clavatus C.Agardh, 1822 (uncertain)
  » Species Fucus coarctatus Schousboe (uncertain)
  » Species Fucus conoides Forssk. (uncertain)
  » Species Fucus deformis Esper, 1800 (uncertain)
  » Species Fucus denudatus 'Turner' (uncertain)
  » Species Fucus diaphanus Raffeneau Delile (uncertain)
  » Species Fucus dichotomus Sauvageau, 1915 (uncertain)
  » Species Fucus diffusus Hudson, 1778 (uncertain)
  » Species Fucus disciplinalis Bory de Saint-Vincent (uncertain)
  » Species Fucus divaricatus Gunnerus, 1772 (uncertain)
  » Species Fucus emarginatus Vahl (uncertain)
  » Species Fucus felinus Raffeneau Delile (uncertain)
  » Species Fucus fibrilla Esper, 1804 (uncertain)
  » Species Fucus filicinus Hudson, 1762 (uncertain)
  » Species Fucus fimbriatus S.G.Gmelin, 1768 (uncertain)
  » Species Fucus flaccidus J.V.Lamouroux, 1802 (uncertain)
  » Species Fucus flagellaris Esper, 1800 (uncertain)
  » Species Fucus flexilis Wulfen, 1803 (uncertain)
  » Species Fucus forsskaolii Mertens (uncertain)
  » Species Fucus friabilis Clemente, 1807 (uncertain, synonym)
  » Species Fucus fulvescens Esper, 1802 (uncertain)
  » Species Fucus furcatus Stackhouse, 1802 (uncertain)
  » Species Fucus geniculatus S.G.Gmelin, 1768 (uncertain)
  » Species Fucus globulifer Turner, 1819 (uncertain, uncertain taxonomic status subjected to verification)
  » Species Fucus gramineus A.P.de Candolle, 1807 (uncertain)
  » Species Fucus hirtus Bonpland, 1809 (uncertain)
  » Species Fucus humboldtii Bonpland, 1809 (uncertain)
  » Species Fucus humilis Schousboe (uncertain)
  » Species Fucus hypnoides Wulfen, 1787 (uncertain, uncertain taxonomic status subjected to verification)
  » Species Fucus imbricatus Schousboe (uncertain)
  » Species Fucus intermedius Van Goor, 1923 (uncertain)
  » Species Fucus lagascae Clemente, 1807 (uncertain)
  » Species Fucus lichenoides S.G.Gmelin, 1768 (uncertain)
  » Species Fucus lichenoides Goodenough & Woodward, 1797 (uncertain)
  » Species Fucus ligulatus S.G.Gmelin, 1768 (uncertain)
  » Species Fucus lobatus Schousboe (uncertain)
  » Species Fucus lubricus Schousboe (uncertain)
  » Species Fucus mamillaris Esper, 1802 (uncertain)
  » Species Fucus marginalis Schousboe (uncertain)
  » Species Fucus marginalis Wulfen, 1791 (uncertain, uncertain taxonomic status subjected to verification)
  » Species Fucus membranaceus N.L.Burman, 1768 (uncertain)
  » Species Fucus membranifolius Withering, 1796 (uncertain)
  » Species Fucus mesembrianthemi Schousboe (uncertain)
  » Species Fucus nereideus Lightfoot, 1777 (uncertain)
  » Species Fucus ovifrons Weber & D.Mohr, 1805 (uncertain)
  » Species Fucus palmetta S.G.Gmelin, 1768 (uncertain)
  » Species Fucus papillosus S.G.Gmelin, 1768 (uncertain)
  » Species Fucus parksii N.L.Gardner, 1940 (uncertain)
  » Species Fucus pinnatus N.L.Burman, 1768 (uncertain)
  » Species Fucus plumula Esper, 1800 (uncertain)
  » Species Fucus polyphyllus S.G.Gmelin, 1768 (uncertain)
  » Species Fucus potamogetifolius Turra, 1780 (uncertain)
  » Species Fucus pumilus Hudson, 1778 (uncertain)
  » Species Fucus racemosus Esper, 1800 (uncertain)
  » Species Fucus rigidus Turra, 1780 (uncertain)
  » Species Fucus rissoanus Schousboe (uncertain)
  » Species Fucus seta Sprengel, 1809 (uncertain)
  » Species Fucus setaceus Esper, 1808 (uncertain)
  » Species Fucus setaceus Hudson, 1778 (uncertain)
  » Species Fucus setaceus Poiret, 1808 (uncertain)
  » Species Fucus setaceus Wulfen, 1803 (uncertain)
  » Species Fucus siliculosus Linnaeus, 1767 (uncertain)
  » Species Fucus spataeformis Esper, 1808 (uncertain)
  » Species Fucus spermophorus Linnaeus, 1767 (uncertain)
  » Species Fucus sphaerocephalus Esper, 1804 (uncertain)
  » Species Fucus squamulosus Turner, 1809 (uncertain)
  » Species Fucus tendo Linnaeus, 1753 (uncertain)
  » Species Fucus tenuissimus Esper, 1800 (uncertain)
  » Species Fucus tetragonus Goodenough & Woodward, 1797 (uncertain)
  » Species Fucus ulvoides Turner, 1809 (uncertain)
  » Species Fucus uncialis Schousboe (uncertain)
  » Species Fucus undulatus J.F.Gmelin, 1792 (uncertain)
  » Species Fucus uniformis Esper, 1800 (uncertain)
  » Species Fucus vermicularis S.G.Gmelin, 1768 (uncertain, uncertain taxonomic status subjected to verification)
  » Species Fucus virens Schousboe (uncertain)
  » Species Fucus vulpinus Esper, 1800 (uncertain)
  » Species Fucus zeylanicus Retzius, 1791 (uncertain)