[1] This site consists of two fields, one at Whittlesford and one at Thriplow with a total area of 55.6 ha (137.4 acres).

These depressions provide suitable habitat for grass-poly (Lythrum hyssopifolia), a very rare plant in Great Britain.

Other plants growing in this specialised habitat include toad rush (Juncus bufonius), greater plantain (Plantago major), knotgrass (Polygonum aviculare), redshank (Persicaria maculosa) and the very local tasteless water-pepper (Persicaria mitis).

There is a requirement for both flooding and ploughing of the site to maintain this specialised community and provide suitable conditions for it to continue.

[1] Another rarity found at this site is the fairy shrimp (Chirocephalus diaphanus),[1] here at the most northerly end of its range, a crustacean, protected under the Wildlife and Countryside Act 1981.