Potteric Carr has a bedrock geology of Sherwood Sandstone dating back to the Triassic period. This is overlain with drift deposits of marls, clays and peat. Railway embankments and trackbeds criss-cross the site, with Magnesian Limestone imported from local quarries for their construction which has resulted in pockets of higher pH. Most grassland on the Reserve is neutral. Other habitats vary from open water to mature broadleaved woodland, with Phragmites reedswamp, wet willow-Salix carr, and a number of other vegetation types within the 500 acre (203ha) site.
This has resulted in an varied mixture of flowering plants and ferns, including some specialised or uncommon species for South Yorkshire. Interesting plants include:
Wall Rue Asplenium
ruta-muraria, Old Man's Beard Clematis vitalba, Greater Spearwort Ranunculus
lingua, Heath Dog
Violet Viola canina,
Sand Spurrey Spergularia
rubra,
Hedgerow Cranesbill Geranium pyrenaicum,
Buckthorn Rhamnus
catharticus, Bird's Foot Ornithopus
perpusillus,
Water Starwort Callitriche stagnalis, Water Violet Hottonia palustris,
Small Cudweed Logfia minima, Lesser Water
Plantain Baldellia ranunculoides,
Blunt-flowered Rush Juncus
subnodulosus, Tussock Sedge Carex paniculata,
Cyperus Sedge C.
pseudo cyperus, Pepperwort Lepidium campestre,
Wood Small Reed Calamagrostis epigeios,
Purple Small Reed C. canescens, Water Soldier Stratiotes aloides and Fen Pondweed Potomogeton coloratus.
Yellow Bird's-nest Monotropa hypopitys, found in 1972, is now thought to be extinct here.
Bee Orchid, Potteric Carr, 21st June 2010 © Helen Womack