Description: Thallus a broad flat membrane, two cells thick and distinctly olive green in colour, growing to form a broad flat blade 30 cms long. The blade may be lobed, devided or torn. Cells mostly irregularly arranged, generally with only one pyrenoid.

Habitat: Lower littoral and sublittoral on rocks in shaded sites.

Distribution: A southern species in the British Isles: south England, Co. Clare in Ireland and the Channel Islands. Europe: Mediterranean, Spain and France. Further afield: the Canary Islands.

Similar Species: Ulva lactuca and Ulva rigida, The cells of the former are arranged in more or less curved rows, the latter has microscopic teeth at the base of the thallus.

Key Identification Features:

• Large flat blade, two cells thick and olive green in colour.

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

iNaturalist: Ulva olivascens at iNaturalist World Species Observations database.

WoRMS: Ulva olivascens at World Register of Marine Species. Accepted name: Umbraulva dangeardii M.J.Wynne & G.Furnari, 2014. AphiaID: 840293.

Classification: Biota; Plantae; Viridiplantae; Chlorophyta; Chlorophytina; Ulvophyceae; Ulvales; Ulvaceae; Ulva