Radiofilum
{{short description|Genus of algae}}
{{Automatic taxobox
| image = Radiofilum conjunctivum 358633818.jpg
| image_caption = Radiofilum conjunctivum
| taxon = Radiofilum
| authority = Schmidle, 1894
| type_species = Radiofilum conjunctivum
| type_species_authority = Schmidle
| subdivision_ranks = Species
| subdivision =
}}
Radiofilum is a genus of green algae in the class Chlorophyceae.{{AlgaeBase genus|name=Radiofilum|id=43491}} It is a freshwater genus; they are often found in soft, boggy or acidic waters.{{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 }}
Radiofilum consists of unbranched filaments of cells, surrounded by a very thin mucilage layer. Cells are bead-like, spherical or compressed. The cell wall consists of two halves, and there is a ring around the middle of the cell where the two halves are joined. Cells contain a chloroplast is parietal and contains one or more pyrenoids.
The genus Radiofilum as currently circumscribed appears to be a polyphyletic grouping of species. Some work has been done to transfer species to other genera,{{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 }} including Interfilum and Flintia.{{cite journal|title=Flintia, gen. nov. a replacement genus name for the invalid genus name Parallela E.A.Flint (Microsporaceae, Chlorophyceae)|last1= Molinari-Novoa|first1=E. A.|last2=Guiry|first2=M. D.|date=2020|journal=Notulae Algarum|volume=168|pages=1–3}} The type species, Radiofilum conjunctivum, belongs to the class Trebouxiophyceae and is phylogenetically close to the genus Microthamnion.