{{Short description|Genus of seaweeds}} {{Other uses|List of plants known as sea lettuce}} {{Automatic taxobox | name = Sea lettuce | image = Meersalat-Ulva-lactuca.jpg | image_caption = ''Ulva lactuca'' | taxon = Ulva | authority = Linnaeus, 1753 | subdivision_ranks = Species | subdivision = See text | synonyms_ref = <ref name="hayden"/> | synonyms = *''Enteromorpha''<small> Link ''in'' Nees, 1820</small>. }} [[File:Tufts of gutweed in Gullmarsfjorden at Sämstad 1.jpg|thumb|''Ulva intestinalis'']]
The '''sea lettuces''' comprise the genus '''''Ulva''''', a group of edible green algae that are widely distributed along the coasts of the world's oceans. The type species within the genus ''Ulva'' is ''Ulva lactuca'', ''lactuca'' being Latin for "lettuce". The genus also includes the species previously classified under the genus '''''Enteromorpha''''',<ref name="hayden">{{cite journal|author1=Hillary S. Hayden|author2=Jaanika Blomster|author3=Christine A. Maggs|author-link3=Christine Maggs|author4=Paul C. Silva|author5=Michael J. Stanhope |author6=J. Robert Waaland|name-list-style=amp|year=2003|title=Linnaeus was right all along: ''Ulva'' and ''Enteromorpha'' are not distinct genera |journal=European Journal of Phycology|volume=38|issue=3|pages=277–294|doi=10.1080/1364253031000136321|issn=1469-4433 |url=http://www.biosciences-labs.bham.ac.uk/callowj/ent/Hayden_Blomster_Maggs.pdf|url-status=dead |archiveurl=https://web.archive.org/web/20110807202051/http://www.biosciences-labs.bham.ac.uk/callowj/ent/Hayden_Blomster_Maggs.pdf |archivedate=2011-08-07|citeseerx=10.1.1.330.5106|s2cid=18856367}}</ref> which are known under the common name '''green nori'''.<ref name="ab">{{cite web|url=http://www.algaebase.org/search/genus/detail/?genus_id=30&-session=abv4:CB54B42A052142EC7ByyTs61E2FB|title=''Enteromorpha'' Link in Nees, 1820|author1=M.D. Guiry |author2=G.M. Guiry |name-list-style=amp |year=2012|website=AlgaeBase|publisher=National University of Ireland|access-date=February 11, 2012}}</ref>
==Description== Individual blades of ''Ulva'' can grow to be more than 400 mm (16 in) in size, but this occurs only when the plants are growing in sheltered areas. A macroscopic alga which is light to dark green in colour, it is attached by disc holdfast. Their structure is a leaflike flattened thallus.<ref>{{Cite web|title=Sea lettuce {{!}} green algae|url=https://www.britannica.com/science/sea-lettuce|access-date=2021-02-23|website=Encyclopedia Britannica|language=en}}</ref><ref>Burrows, E.M. 1991. ''Seaweeds of the British Isles. Volume 2 Chlorophyta.'' Natural History Museum, {{ISBN|0-565-00981-8}}</ref>
==Nutrition and contamination== Sea lettuce is eaten by a number of different sea animals, including manatees and the sea slugs known as sea hares.<ref>{{cite journal |last=Carefoot |first=T.H. |year=1979 |title=Artificial diets for sea hares |journal=Canadian Journal of Zoology |volume=57 |issue=11 |pages=2271–2273 |doi=10.1139/z79-295}}</ref>
Many species of sea lettuce are a food source for humans in Scandinavia, Great Britain, Ireland, China, and Japan (where this food is known as ''aosa''). Sea lettuce as a food for humans is eaten raw in salads and cooked in soups. It is high in protein, soluble dietary fiber, and a variety of vitamins and minerals, especially iron.<ref name=Yaich>{{citation |author1=Yaich, H. |author2=Garna, H. |author3=Besbes, S. |author4=Paquot, M. |author5=Blecker, C. |author6=Attia, H. |year=2011 |title=Chemical composition and functional properties of ''Ulva lactuca'' seaweed collected in Tunisia |journal=Food Chemistry |volume=128 |issue=4 |pages=895–901 |doi=10.1016/j.foodchem.2011.03.114 |s2cid=85407130}}</ref> Enhances flavor and fortifies bread when chopped and mixed into the dough before baking.<ref>{{Cite journal |last1=D-S |first1=Stef |last2=Rivis |first2=A |last3=Trasca |first3=TI |display-authors=etal |title=The Enrichment of Bread with Algae Species |journal=Scientific Papers Series D: Animal Science |date=2022 |volume=65 |issue=1 |pages=558–563 |url=https://search.ebscohost.com/login.aspx?direct=true&db=a9h&AN=159374048&site=eds-live&scope=site |access-date=2026-01-28}}</ref><ref>{{cite book |last=Kort |first=Robin |title=''The Coastal Forager’s Cookbook'' |publisher=Touchwood Editions |year=2023 |isbn=978-1771514088 |url=https://touchwoodeditions.com/products/the-coastal-foragers-cookbook |format=Hardback}}</ref> Contamination with toxic heavy metals at certain sites where it can be collected makes it dangerous for human consumption.<ref name=Yaich/>
==Health concerns== In August 2009, unprecedented amounts of these algae washed up on the beaches of Brittany, France, causing a major public health scare as it decomposed. The rotting leaves produced large quantities of hydrogen sulfide, a toxic gas. In one incident near Saint-Michel-en-Grève, a horse rider lost consciousness and his horse died after breathing the seaweed fumes; in another, a lorry driver driving a load of decomposing sea lettuce passed out, crashed, and died, with toxic fumes claimed to be the cause.<ref name="bbc">{{Cite news |title=Seaweed suspected in French death |publisher=BBC |date=September 7, 2009 |url=https://news.bbc.co.uk/2/hi/europe/8242649.stm |access-date=September 7, 2009}}</ref> Environmentalists blamed the phenomenon on excessive nitrogenous compounds washed out to sea from improper disposal of pig and poultry slurry from industrial farms, and from chemical products and slurry used as fertilisers in arable farming.
==Species== Species in the genus ''Ulva'' include:<ref name="worms">{{cite WoRMS|author=M.D. Guiry|year=2012|id=144296 |title=''Ulva'' Linnaeus, 1753 |db=algae|accessdate=February 11, 2012}}</ref>
;Accepted species {{Div col}} *''Ulva acanthophora''<small> (Kützing) Hayden, Blomster, Maggs, P.C. Silva, Stanhope & J.R. Waaland, 2003</small> *''Ulva anandii''<small> Amjad & Shameel, 1993</small> *''Ulva arasakii''<small> Chihara, 1969</small> *''Ulva atroviridis''<small> Levring, 1938</small> *''Ulva australis'' <small>Areschoug, 1854</small> *''Ulva beytensis''<small> Thivy & Sharma, 1966</small> *''Ulva bifrons''<small> Ardré, 1967</small> *''Ulva brevistipita''<small> V.J. Chapman, 1956</small> *''Ulva burmanica''<small> (Zeller) De Toni, 1889</small> *''Ulva californica''<small> Wille, 1899</small> *''Ulva chaetomorphoides''<small> (Børgesen) Hayden, Blomster, Maggs, P.C. Silva, M.J. Stanhope & J.R. Waaland, 2003</small> *''Ulva clathrata''<small> (Roth) C. Agardh, 1811</small> *''Ulva compressa''<small> Linnaeus, 1753</small> *''Ulva conglobata''<small> Kjellman, 1897</small> *''Ulva cornuta''<small> Lightfoot, 1777</small> *''Ulva covelongensis''<small> V. Krishnamurthy & H. Joshi, 1969</small> *''Ulva crassa''<small> V.J. Chapman, 1956</small> *''Ulva crassimembrana''<small> (V.J. Chapman) Hayden, Blomster, Maggs, P.C. Silva, M.J. Stanhope & J.R. Waaland, 2003</small> *''Ulva curvata''<small> (Kützing) De Toni, 1889</small> *''Ulva denticulata''<small> P.J.L. Dangeard, 1959</small> *''Ulva diaphana''<small> Hudson, 1778</small> *''Ulva elegans''<small> Gayral, 1960</small> *''Ulva enteromorpha''<small> Le Jolis, 1863</small> *''Ulva erecta''<small> (Lyngbye) Fries</small> *''Ulva expansa''<small> (Setchell) Setchell & N.L. Gardner, 1920</small> *''Ulva fasciata''<small> Delile, 1813</small> *''Ulva flexuosa''<small> Wulfen, 1803</small> *''Ulva geminoidea''<small> V.J. Chapman, 1956</small> *''Ulva gigantea''<small> (Kützing) Bliding, 1969</small> *''Ulva grandis''<small> Saifullah & Nizamuddin, 1977</small> *''Ulva hookeriana''<small> (Kützing) Hayden, Blomster, Maggs, P.C. Silva, M.J. Stanhope & J.R. Waaland</small> *''Ulva hopkirkii''<small> (M'Calla ex Harvey) P. Crouan & H. Crouan</small> *''Ulva howensis''<small> (A.H.S. Lucas) Kraft, 2007</small> *''Ulva indica''<small> Roth, 1806</small> *''Ulva intestinalis''<small> Linnaeus, 1753</small> *''Ulva intestinaloides''<small> (R.P.T. Koeman & Hoek) Hayden, Blomster, Maggs, P.C. Silva, M.J. Stanhope & J.R. Waaland, 2003</small> *''Ulva javanica''<small> N.L. Burman, 1768</small> *''Ulva kylinii''<small> (Bliding) Hayden, Blomster, Maggs, P.C. Silva, M.J. Stanhope & J.R. Waaland, 2003</small> *''Ulva lactuca''<small> Linnaeus, 1753</small> *''Ulva laetevirens''<small> J.E. Areschoug, 1854</small> *''Ulva laingii''<small> V.J. Chapman, 1956</small> *''Ulva linearis''<small> P.J.L. Dangeard, 1957</small> *''Ulva linza''<small> Linnaeus, 1753</small> *''Ulva lippii''<small> Lamouroux</small> *''Ulva litoralis''<small> Suhr ex Kützing</small> *''Ulva littorea''<small> Suhr</small> *''Ulva lobata''<small> (Kützing) Harvey, 1855</small> *''Ulva maeotica''<small> (Proshkina-Lavrenko) P.M.Tsarenko, 2011</small> *''Ulva marginata''<small> (J. Agardh) Le Jolis</small> *''Ulva micrococca''<small> (Kützing) Gobi</small> *''Ulva mutabilis''<small> Föyn, 1958</small> *''Ulva neapolitana''<small> Bliding, 1960</small> *''Ulva nematoidea''<small> Bory de Saint-Vincent, 1828</small> *''Ulva ohnoi''<small> Hiraoka & Shimada, 2004</small> *''Ulva olivascens''<small> P.J.L. Dangeard</small> *''Ulva pacifica''<small> Endlicher</small> *''Ulva papenfussii''<small> Pham-Hoang Hô, 1969</small> *''Ulva parva''<small> V.J. Chapman, 1956</small> *''Ulva paschima''<small> Bast</small> *''Ulva patengensis''<small> Salam & Khan, 1981</small> *''Ulva percursa''<small> (C. Agardh) C. Agardh</small> *''Ulva pertusa''<small> Kjellman, 1897</small> *''Ulva phyllosa''<small> (V.J. Chapman) Papenfuss</small> *''Ulva polyclada''<small> Kraft, 2007</small> *''Ulva popenguinensis''<small> P.J.L. Dangeard, 1958</small> *''Ulva porrifolia''<small> (S.G. Gmelin) J.F. Gmelin</small> *''Ulva profunda''<small> W.R. Taylor, 1928</small> *''Ulva prolifera''<small> O.F.Müller, 1778</small> *''Ulva pseudocurvata''<small> Koeman & Hoek, 1981</small> *''Ulva pseudolinza''<small> (R.P.T. Koeman & Hoek) Hayden, Blomster, Maggs, P.C. Silva, M.J. Stanhope & J.R. Waaland, 2003</small> *''Ulva pulchra''<small> Jaasund, 1976</small> *''Ulva quilonensis''<small> Sindhu & Panikkar, 1995</small> *''Ulva radiata''<small> (J. Agardh) Hayden, Blomster, Maggs, P.C. Silva, M.J. Stanhope & J.R. Waaland, 2003</small> *''Ulva ralfsii''<small> (Harvey) Le Jolis, 1863</small> *''Ulva ranunculata''<small> Kraft & A.J.K. Millar, 2000</small> *''Ulva reticulata''<small> Forsskål, 1775</small> *''Ulva rhacodes''<small> (Holmes) Papenfuss, 1960</small> *''Ulva rigida''<small> C. Agardh, 1823</small> *''Ulva rotundata''<small> Bliding, 1968</small> *''Ulva saifullahii''<small> Amjad & Shameel, 1993</small> *''Ulva serrata''<small> A.P.de Candolle</small> *''Ulva simplex''<small> (K.L. Vinogradova) Hayden, Blomster, Maggs, P.C. Silva, M.J. Stanhope & J.R. Waaland, 2003</small> *''Ulva sorensenii''<small> V.J. Chapman, 1956</small> *''Ulva spinulosa''<small> Okamura & Segawa, 1936</small> *''Ulva stenophylla''<small> Setchell & N.L. Gardner, 1920</small> *''Ulva sublittoralis''<small> Segawa, 1938</small> *''Ulva subulata''<small> (Wulfen) Naccari</small> *''Ulva taeniata''<small> (Setchell) Setchell & N.L. Gardner, 1920</small> *''Ulva tanneri''<small> H.S. Hayden & J.R. Waaland, 2003</small> *''Ulva tenera''<small> Kornmann & Sahling</small> *''Ulva torta''<small> (Mertens) Trevisan, 1841</small> *''Ulva tuberosa''<small> Palisot de Beauvois</small> *''Ulva uncialis''<small> (Kützing) Montagne, 1850</small> *''Ulva uncinata''<small> Mohr</small> *''Ulva uncinata''<small> Mertens</small> *''Ulva usneoides''<small> Bonnemaison</small> *''Ulva utricularis''<small> (Roth) C. Agardh</small> *''Ulva utriculosa''<small> C. Agardh</small> *''Ulva uvoides Bory''<small> de Saint-Vincent</small> *''Ulva ventricosa''<small> A.P.de Candolle</small> {{div col end}} ;Nomina dubia *''Ulva costata''<small> Wollny, 1881 </small> *''Ulva repens''<small> Clemente, 1807 </small> *''Ulva tetragona''<small> A.P.de Candolle, 1807 </small>
A newly discovered Indian endemic species of ''Ulva'' with tubular thallus indistinguishable from ''Ulva intestinalis'' has been formally established in 2014 as ''Ulva paschima'' Bast.<ref>BAST, F., JOHN, A.A. AND BHUSHAN, S. 2014. Strong endemism of bloom-forming tubular ''Ulva'' in Indian west coast, with description of ''Ulva paschima'' Sp. Nov. (Ulvales, Chlorophyta. [http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0109295 PLoS ONE 9(10): e109295]. doi:10.1371/journal.pone.0109295</ref> Ten new species have been discovered in New Caledonia: ''Ulva arbuscula'', ''Ulva planiramosa'', ''Ulva batuffolosa'', ''Ulva tentaculosa'', ''Ulva finissima'', ''Ulva pluriramosa'', ''Ulva scolopendra'' and ''Ulva spumosa''. <ref>Lagourgue, L ''et al'' 2022 The new species of ''Ulva'' (Ulvophyceae, Chlorophyta) discovered in New Caledonia genetic and morphological and diversity, and bloom potential. ''British Phycological Society'' '''57''';458 - 478.</ref>
==See also== * Green laver {{commons category|Ulva (genus)}}
==References== {{Reflist}}
==Further reading== {{refbegin}} * {{cite journal |last=Beer |first=Sven |date=2023 |title=Photosynthetic traits of ubiquitous and prolific macroalga ''Ulva'' (Chlorophyta): a review |journal=European Journal of Phycology |volume=58 |pages=390–398 |doi=10.1080/09670262.2022.2150894 |access-date=27 January 2025|url=https://doi.org/10.1080/09670262.2022.2150894|url-access=subscription }} {{refend}}
==External links== * [http://www.mbari.org/staff/conn/botany/greens/anna/frontpages/default.htm Marine botany: Ulva] {{Webarchive|url=https://web.archive.org/web/20110516104905/http://www.mbari.org/staff/conn/botany/greens/anna/frontpages/default.htm |date=2011-05-16 }} * {{cite web |url=http://www.algaebase.org/GeneraDetail.lasso?genus_id=33 |website=AlgaeBase |title=''Ulva'' Linnaeus 1753: 1163 |author1=C. Tanner |author2=Robert Wilkes |name-list-style=amp |date=2005-02-17}} * [https://news.bbc.co.uk/2/hi/europe/8195180.stm Toxic seaweed clogs French coast Caledonia: morphological diversity, and bloom potential.t (BBC)]
{{Taxonbar|from=Q1109330}} {{Authority control}}
Category:Ulvaceae Category:Edible seaweeds Category:Edible algae