Rhôs pastures are enclosed species-rich purple moor-grass and rush pastures. On Dartmoor they are found in valley systems away from the open moor, usually in a mosaic together with wet woodland, other species-rich grasslands and oakwood. Dartmoor has 1,200 hectares of this habitat, representing 20% of the English resource
The most distinctive plants of this habitat on Dartmoor are the meadow thistle, devil’s-bit scabious, heath spotted orchid and saw-wort, all colourful plants. They grow in amongst either purple moor-grass or sharp-flowered rush and there may be some creeping willow present. Other plants that can be found include ivy-leaved bellflower, lesser spearwort, marsh thistle, sneezewort, greater bird’s foot trefoil and marsh violet .
Rhôs pasture is home to marbled white butterflies, which can be abundant, small pearl-bordered fritillary and the highly protected marsh fritillary which is found in colonies representing about 20% of the English resource. One of Britain’s rarest damselflies, the southern damselfly, also occurs in a single Rhôs pasture on Dartmoor. The rare narrow-bordered bee hawkmoth, which feeds on devil’s bit scabious can also be found, often in association with marsh fritillary.