Guide to Liverworts of Oregon: Riccia fluitans L.
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Genkey 71a floating aquatic > Riccia fluitans
Synonym: None.
Special Status: None.
Recognition: This plant floats under the surface, unlike Ricciocarpus, which floats on the surface. Its ribbons are narrow, less than 2 mm wide, and fork very regularly.
Distribution: In ponds and still backwaters; sporadically distributed around the state; most records are from Willamette Valley.
Comments: There are several species closely related to Riccia fluitans which probably occur regularly in our region. Special attention should be given to the small floating aquatic liverworts, especially partially stranded forms. Riccia sullivantii is one of these, which Zander (2023, FNA v. 29, in prep) treats as Riccia huebeneneiana subsp. sullivantii. He also offers a key to four of these recognized as nomina nuda.
Riccia fluitans Frye & Clark 1937, p. 37.
Distal aspect. Sabino Canyon, Pima Co., Arizona. Olmstead et al. 537 (CAS). SEM by W.T. Doyle SEM.
Proximal face. Sabino Canyon, Pima Co., Arizona. Olmstead et al. 537 (CAS). SEM by W.T. Doyle SEM.
Tetrad. Sabino Canyon, Pima Co., Arizona. Olmstead et al. 537 (CAS). SEM by W.T. Doyle SEM.