The descriptive text, below the map, is from the Cornish Red Data Book (2009). The map on this web page depicts the organisms distribution and shows the records made pre-2000 and those made since.
Native; Suboceanic Southern-temperate element. Confined to south Devon. It can occur elsewhere as an introduction or as a casual, such as on railway ballast in Hertfordshire and on railway gravels in Lancashire.
00 Regional Distribution
\hyphpar0\sl288\slmult1 Formerly at Loe Bar. Last recorded in 1915.
00 Habitat & Ecology
An annual of shingly pool margins where water levels fluctuate.
\hyphpar0\sl288\slmult1 Its loss from Cornwall is believed to have been caused by a lack of fluctuating water level in Loe Pool following man-made controls.
Listed (long list) as a globally threatened/declining species (BSGR, 1995).
I.J. Bennallick, S. Board, C.N. French, P.A. Gainey, C. Neil, R. Parslow, A. Spalding and P.E. Tompsett. eds. 2009. Red Data Book for Cornwall and the Isles of Scilly. 2nd Edition.Croceago Press.
The Cornish Red Data Book Project was led by the Cornwall and Isles of Scilly Federation for Biological Recorders (CISFBR). The full text and species accounts (minus the maps) are available on the CISFBR website.