{{Short description|Species of marine chlorophyte green alga}} {{Speciesbox |image = Tufts of gutweed in Gullmarsfjorden at Sämstad 1.jpg |genus = Ulva |species = intestinalis |authority = L. | synonyms = * ''Enteromorpha intestinalis'' }} [[File:Marine algae in Brofjorden.jpg|thumb|Large green lumps of ''Ulva intestinalis'' floating among brown algae in Brofjorden]]

'''''Ulva intestinalis''''' is a green alga in the family Ulvaceae, known by the common names '''sea lettuce''', '''green bait weed''', '''gutweed''',<ref>{{Cite web |title=Gutweed |url=http://www.kscience.co.uk/as/module5/seashore_web_site/organisms/enteromorpha.htm |access-date=2023-12-05 |website=www.kscience.co.uk |archive-date=2024-12-26 |archive-url=https://web.archive.org/web/20241226171117/http://kscience.co.uk/as/module5/seashore_web_site/organisms/enteromorpha.htm |url-status=dead }}</ref> and '''grass kelp'''.<ref>[http://nagisa.cbm.usb.ve/cms/shore-dwellers/grass-kelp-gutweed/ Grass-kelp, Gutweed] {{Webarchive|url=https://web.archive.org/web/20150620093057/http://nagisa.cbm.usb.ve/cms/shore-dwellers/grass-kelp-gutweed/ |date=2015-06-20 }}</ref> Until they were reclassified by genetic work completed in the early 2000s, the tubular members of the sea lettuce genus ''Ulva'' were placed in the genus ''Enteromorpha''.<ref name="Guiry07">Guiry, M.D., John, D.M., Rindi, F. and McCarthy, T.K. (Eds) 2007. ''New Survey of Clare Island. Volume 6: The Freshwater and Terrestrial Algae.'' p. 23. Royal Irish Academy. {{ISBN|978-1904890-31-7}}</ref>

==Distribution== Generally world-wide.<ref name = "Burrows 91">Burrows, E.M. 1991. ''Seaweeds of the British Isles. Volume 2 Chlorophyta''. British Museum (Natural History). {{ISBN|0-565-00981-8}}</ref> It can be found in the Bering Sea near Alaska, Aleutian Islands, Puget Sound, Japan, Korea, Mexico, Philippines, and Russia.<ref>{{cite web|url= http://www.seaweedsofalaska.com/species.asp?SeaweedID=12|title=''Ulva intestinalis'' |publisher=Seaweed of Alaska|access-date=March 24, 2013}}</ref> It can also be found in Israel, as well as in such European countries as Azores, Belgium, Denmark, Ireland, Norway, Poland, and in such seas as the Baltic, and Mediterranean Sea. It is also found in the shores of the Pacific Ocean including in New Zealand.<ref name=worms>{{cite WoRMS|author=Guiry, M.D.|year=2012|title=Ulva intestinalis Linnaeus, 1753|id=234471|accessdate=March 24, 2013}}</ref><ref name=":0">{{Cite book|title=New Zealand seaweeds : an illustrated guide|last=W. A.|first=Nelson|publisher=Te Papa Press|year=2013|isbn=9780987668813|location=Wellington, New Zealand|pages=42|oclc=841897290|author-link=Wendy Nelson (marine scientist)}}</ref>

==Description== The fronds have branches and are completely tubular expanding in width to mid-thallus, reaching 15&nbsp;cm long or more. The cells are irregularly arranged and the chloroplast is hood-shaped and placed to one side, generally with only one pyrenoid.<ref name="Guiry07"/><ref name = "Burrows 91"/> The species may be {{convert|10|-|30|cm}} long and {{convert|6|-|18|mm}} wide. They have rounded tips as well.<ref>{{cite web|url= http://www.marlin.ac.uk/speciesfullreview.php?speciesID=4540|title=Gut weed - Ulva intestinalis|access-date=March 24, 2013}}</ref> The alga may be reproductive at all times of the year, and has a life-cycle with alternation of generations, in which the gametophyte and sporophyte are isomorphic, having identical morphology.<ref name = "Burrows 91"/> In some references the species (''Ulva intestinalis'') is treated as two subspecies: ssp. ''intestinalis'' (L.) Link and ssp. ''compressa'' (L.) Link.<ref name = "Burrows 91"/><ref>Morton, O. 1994. ''Marine Algae of Northern Ireland.'' Ulster Museum {{ISBN|0 900761 28 8}}</ref>

==In other languages== *{{langx|da|tarm-rørhinde}} *{{langx|nl|echt darmwier}} *{{langx|fr|entéromorphe}} *{{langx|de|Darmtang, gemeiner Darmtang}} *{{langx|no|tarmgrønske}} *{{langx|pl|sałata, taśma, watka}}<ref name=worms/> *{{langx|sv|tarmalg}} *{{langx|th|สาหร่ายไส้ไก่}} *{{langx|pt|erva-patinha}}

==References== {{Commons category}} {{Reflist}}

{{Taxonbar|from=Q2708229}}

Category:Ulvaceae Category:Edible seaweeds Category:Plants described in 1753 Category:Botanical taxa named by Carl Linnaeus