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.

Regional Distribution

Formerly at Loe Bar. Last recorded in 1915.

Habitat & Ecology

An annual of shingly pool margins where water levels fluctuate.

Threats

Its loss from Cornwall is believed to have been caused by a lack of fluctuating water level in Loe Pool following man-made controls.

Conservation

Listed (long list) as a globally threatened/declining species (BSGR, 1995).