{{Short description|Genus of algae}} {{Automatic taxobox | image = Characium hookeri.png | image_caption = ''Characium hookeri'' | taxon = Characium | authority = A.Braun in Kützing, 1849 | type_species = ''Characium sieboldii'' | type_species_authority = A.Braun<ref name="Algaebase"/> | subdivision_ranks = Species | subdivision_ref = <ref name="Algaebase">{{AlgaeBase genus|id= 37473|name= Characium | access-date=2023-09-26 }}</ref> | subdivision = See text }}
'''''Characium''''' is a genus of green algae in the family Characiaceae.<ref name="Algaebase"/> It is very commonly found in freshwater habitats, where it is attached to phytoplankton or zooplankton.<ref name=Shubert2014>{{cite book |editor-first1=John D.|editor-last1=Wehr|editor-first2=Robert G.|editor-last2=Sheath|editor-first3=J. Patrick|editor-last3=Kociolek |date= 2014 |edition=2 |title= Freshwater Algae of North America: Ecology and Classification |last1= Shubert|first1=Elliot| last2=Gärtner |first2=Georg |chapter= Chapter 7. Nonmotile Coccoid and Colonial Green Algae |url= |location= |publisher= Elsevier Inc. |page= |isbn=978-0-12-385876-4 }}</ref>
==Description== ''Characium'' consists of single or rarely clustered cells. They are attached to a plant or animal substrate (thus epiphytic or epizoic), via a stalk or a circular pad. The cells have diverse shapes, ranging from fusiform to club-shaped or spherical, and are variously straight, hooked, or S-shaped. Cells usually contain a single parietal chloroplast filling the cell, with a central pyrenoid. In some species, the chloroplasts fragment into multiple plastids, each with one pyrenoid.<ref name=Bicudo_and_Menezes2006>{{cite book | title= Gêneros de Algas de Águas Continentais do Brasil: chave para identificação e descrições | edition=2 | year=2006 | first1=Carlos E. M. |last1=Bicudo | first2=Mariângela | last2= Menezes | publisher= RiMa Editora | pages=508 | isbn= 857656064X }}</ref> Mature cells have one nucleus (are uninucleate).<ref name=Ettl_Gaertner/>
''Characium'' reproduces asexually by zoospores. Zoospores have two flagella.<ref name=Bicudo_and_Menezes2006/>
===Identification=== The genus ''Characium'' is similar to ''Characiopsis'', a type of algae in the class Eustigmatophyceae. The two genera are very similar and have been confused in the past;<ref name="Characiopsis">{{AlgaeBase genus|id= 43814|name= Characiopsis | access-date=2023-09-26 }}</ref> however, ''Characium'' produces starch to store excess carbon and thus stains brown to purple in Lugol's iodine solution, while ''Characiopsis'' does not.<ref name=Matthews>{{cite journal | date = 2016 | last1=Matthews | first1=Robin A. | title=Freshwater Algae in Northwest Washington, Volume II, Chlorophyta and Rhodophyta | url= https://cedar.wwu.edu/cedarbooks/1/ | journal = A Collection of Open Access Books and Monographs | publisher = Western Washington University | doi=10.25710/fctx-n773 }}</ref> Many other similar segregate genera have been named. These include ''Deuterocharacium'', which differs in having chloroplasts without pyrenoids,<ref>{{AlgaeBase genus | id=47394 | name= Deuterocharacium | access-date=2023-10-09 }}</ref> and ''Characiopodium'', with multinucleate mature cells.<ref name=Ettl_Gaertner>{{cite book|last1=Ettl|first1=Hanuš|last2=Gärtner|first2=Georg|title=Syllabus der Boden-, Luft- und Flechtenalgen|edition=2nd|date=2013|publisher=Springer-Verlag|isbn=9783642394614|language=de}}</ref>
Identification of species depends on the shapes and sizes of the cell body, as well as the stipe with which the body is attached.<ref name=Algaebase/>
==Species list== {{Div col}} * ''C. acuminatum'' * ''C. ambiguum'' * ''C. angustum'' * ''C. astipitatum'' * ''C. braunii'' * ''C. bulgariense'' * ''C. cerassiforme'' * ''C. conicum'' * ''C. epipyxis'' * ''C. giganteum'' * ''C. groenlandicum'' * ''C. guttula'' * ''C. heteromorphum'' * ''C. limneticum'' * ''C. marinum'' * ''C. nasutum'' * ''C. obtusum'' * ''C. ornithocephalum'' * ''C. ovale'' * ''C. polymorphum'' * ''C. prodani'' * ''C. pseudopyriforme'' * ''C. pyriforme'' * ''C. rostratum'' * ''C. saccatum'' * ''C. sieboldii'' * ''C. strictum'' * ''C. substrictum'' * ''C. subulatum'' * ''C. tenue'' * ''C. terrestre'' * ''C. urnigerum'' * ''C. westianum'' {{Div col end}}
==References== {{Reflist|1}}
{{Taxonbar|from=Q5073708}}
Category:Sphaeropleales genera Category:Sphaeropleales
{{Chlorophyceae-stub}}