Desmarestia

{{short description|Genus of brown algae}}

{{about||the fairy called gruagach|Brownie (folklore)|the other seaweed called landlady's wig|Ahnfeltia plicata|the other genus called mermaid's hair|Cladophora}}

{{Automatic taxobox

|image = Desmarestia viridis Crouan.jpg

|image_caption = Desmarestia viridis

|image_alt = Desmarestia viridis

|taxon = Desmarestia

|authority = J.V.Lamouroux, 1813{{cite journal|last1=Lamouroux|first1=Jean Vincent Félix|authorlink1=Jean Vincent Félix Lamouroux|title=Essai sur les genres de la famille des thalassiophytes non articulées|journal=Annales du Muséum d'Histoire Naturelle, Paris|date=1813|volume=20|pages=43–45|url=http://img.algaebase.org/pdf/562E29B40301733B85MQrj41D8EE/17071.pdf|accessdate=11 December 2017|language=French|oclc=2099267}}

|type_species = Desmarestia aculeata

|type_species_authority = (L.) J.V.Lamouroux

}}

Desmarestia is a genus of brown algae found worldwide. It is also called acid weed, acid kelp, acidweed,{{Cite journal|last1=Watson|first1=Jane|title=Spatial and temporal variation in kelp forest composition off the NW coast of Vancouver Island, British Columbia|url=http://cedar.wwu.edu/ssec/2014ssec/Day1/106/|journal=Salish Sea Ecosystem Conference|accessdate=12 December 2017|language=English|date=30 April 2014|quote=In general, annual species such as Acid Weed (Desmarestia spp,) were highly variable in abundance}}{{cite web|last1=Warneke|first1=Alex|title=These are a few of my favorite species: Desmarestia|url=http://www.deepseanews.com/2014/12/these-are-a-few-of-my-favorite-species-desmarestia/|website=Deep Sea News|accessdate=12 December 2017|language=English|date=5 December 2014|quote=Rightly named “Acid Weed,” the internal pH of Desmarestia has been estimated as low as 0.6 pH.}} {{lang|fr|oseille de mer}}, sea sorrel,{{cite book|last1=Dickinson|first1=Carola I.|title=British Seaweeds|date=1963|publisher=Eyre & Spottiswoode|page=76|url=https://books.google.com/books?id=yv8dMQAACAAJ&q=sea+sorrel|accessdate=13 December 2017|language=English|oclc=1437555|location=London|series=Kew series|volume=3}} {{lang|ja|ウルシグサ}} ({{transl|ja|urushi-gusa}}), {{lang|de|stacheltang}}, mermaid's hair, landlady's wig, or {{lang|ga|gruagach}}.{{cite web |author1= |title=Desmarestia |url=http://surialink.seaplant.net/HANDBOOK/Genera/browns/Desmarestia/Desmarestia.htm |url-status=dead |archive-url=https://web.archive.org/web/20200105213951/http://surialink.seaplant.net/HANDBOOK/Genera/browns/Desmarestia/Desmarestia.htm |archive-date=5 January 2020 |accessdate=13 December 2017 |website=SuriaLink SeaPlants Handbook |language=English}} However, 'sea sorrel' can also specifically refer to Desmarestia viridis. Members of this genus can be either annual or perennial.{{cite web

|url=http://algaebase.org/search/genus/detail/?genus_id=56&-session=abv4:86996EF31afb128815jWx299BF9E

|title=Desmarestia J.V.Lamouroux

|author=M.D. Guiry

|publisher=AlgaeBase

|accessdate=November 5, 2013

}} Annual members of this genus store sulfuric acid in intracellular vacuoles. When exposed to air they release the acid, thereby destroying themselves and nearby seaweeds in the process. They are found in shallow intertidal zones.

Ingesting sulfuric acid can cause severe digestive disturbances.{{cite book|last1=Turner|first1=Nancy J.|last2=von Aderkas|first2=Patrick|title=The North American Guide to Common Poisonous Plants and Mushrooms|date=2009|publisher=Timber Press|location=Portland, OR|isbn=9780881929294|page=116|language=English|chapter=3: Poisonous Plants of Wild Areas|oclc=747112294}} but since sulfuric acid tastes extremely sour, members of the genus are unlikely to be eaten in harmful quantities.

The genus was named in honor of Anselme Gaëtan Desmarest.