Description: Thallus of uniseriate or multiseriate unbranched filaments, growing to a maximum length of 14 mm. Rhizoids are rare. In multiseriate thalli cells are grouped together in packets of two different sizes.

Habitat: Epilithic in the upper littoral and above in the splash zone, also on damp soil, roofs and old walls. Often with Prasiola.

Distribution: British Isles, apparently rare but may be more common than the records indicate. Europe: Netherlands, Baltic Sea, Norway, Faroes and Icelands. Greenland. Atlantic coast of North America: Canada.

Distribution Map from NBN: Rosenvingiella polyrhiza at National Biodiversity Network mapping facility, data for UK.

iNaturalist: Rosenvingiella polyrhiza at iNaturalist World Species Observations database.

WoRMS: Rosenvingiella polyrhiza at World Register of Marine Species.