Purple moor-grass & rush pasture

Purple moor-grass & rush pasture

The marshy grassland known as purple moor grass and rush pasture occurs on poorly drained, mainly acidic sites in lowland areas with high rainfall and wet soils. It is often found with other habitats, such as wet heath, scrub and dry grassland, making up a patchwork of diverse places that support a wide range of insects. It mainly occurs on gently sloping land or on floodplains where it may be periodically flooded during the winter.

In the past, purple moor grass and rush pasture was cut for hay during dry summers, but this practice is now in decline. Today, only a few sites are managed as hay meadows, and most are kept as rough grazing for cattle and horses.

Purple moor-grass & rush pasture at Sirhowy Valley Woodlands

Purple moor-grass & rush pasture is a characteristic habitat of the South Wales coalfield, where they are referred to locally as ‘rhos pastures’. The category encompasses a very wide range of vegetation types, all of which have nature
conservation value. Rhos pastures have been extensively reclaimed for agriculture, lost to development or allowed to deteriorate through lack of management in recent decades, however, and there are now estimated to be only approximatel about 35,000ha of this formerly widespread and common habitat remaining in the whole of Wales, about 160ha of which occur in Blaenau Gwent county borough.

This habitat type can support a diverse and characteristic invertebrate fauna, which may include the rare and protected marsh fritillary butterfly (Eurodryas aurinia) as well as a
number of geographically restricted plant species such as whorled caraway (Carum verticillatum), wavy St John’s-wort (Hypericum undulatum) and petty whin (Genista
anglica). However, none of these species has been recorded to date from the site. Only a very small area of this habitat was present within the site, and this was species-poor and degraded.


Purple moor grass and rush pastures are most frequent in the west of the UK, extending eastwards where wet soils are found. It is estimated that less than 70,000 hectares remain with important concentrations in Cornwall, the Somerset Levels, the New Forest, East Anglia, South Wales and Pembrokeshire.