Marshy Grassland (including Rhos Pasture)

Marshy grasslands are wet habitats that develop on peaty soils which are usually dominated by Purple Moor-grass (Molinia caerulea), Sheep's Fescue (Festuca ovina) and rush (Juncus) species. Unlike fens and swamps, tall reeds are are not an important feature of their phsiognomy and unlike bogs and mires, they are not dominated by bog mosses, although bryophytes can make a significant contribution to their biodiversity. They are often rather species-poor with a predominantly grassy structure broken up by patches of Devil's-bit Scabious (Succisa pratensis), Tormentil (Potentila erecta), Marsh Bird's-foot Trefoil (Lotus uliginosus) and Marsh Thistle (Cirsium palustre). Under some conditions tall herbs like Meadowsweet (Filipendula ulmaria) and Common Valerian (Valeriana officinalis) may be conspicuous. But they can also support a diverse flora of sedges and colouful forbs, particularly when they are flushed by base-rich water. There are a number of important indicator species (axiophytes) linked with base-rich marshy graslands which include Tawny Sedge (Carex hostiana), Broad-leaved Cotton-grass (Eriophorum latifolium), Meadow Thistle (Cirsium dissectum), Fen Bedstraw (Galium uliginosum), Marsh Lousewort (Pedicularis palustris), Common Butterwort (Pinguicola vulgaris) and Marsh Arrow-grass (Triglochin palustris). Other important plant species in biodiverse marshy grasslands include Flea Sedge (Carex pulicaris), Wood Bitter-vetch (Vicia orobus), Saw-wort (Serratula tinctoria), Petty Whin (Genista anglica), Dyer's Greenweed (Genista tinctoria), Ivy-leaved Bellflower (Wahlenbergia hederacea), and Heath Spotted-orchid (Dactylorhiza ericetorum). Viper's Grass (Scozonera humilis) is a very rare species which occurs in marshy grassland in Gower which is otherwise confined to very few sites elsewhere in Britain. Globe Flower (Trollius europaeus), once a feature of some of Glamorgan's, upland marshy grasslands, is now extinct in the county.

Marshy grasslands may also contain mosaics of heath and boggy habitats with large amounts of Deer-sedge (Trichophorum germanicum), Cotton-grasses (Eriophorum angustifolium and Eriophorum vaginatum) and Bog Asphodel (Narthecium ossifragum). Heath species such as Heather (Calluna vulgaris), Cross-leaved Heath (Erica tetralix), Heath Bedstraw (Galium saxatile) and Heath Wood-rush (Luzula multiflora) are often represented.

Marshy grasslands are nationally important habitats and a significant part of Britain's biodiversity. They are best developed in wetter, Oceanic areas and, consequently, are largely a feature of western Britain. They were once a conspicuous feature of the upland landscape of West Glamorgan but they have disappeared from many areas in recent decades as a result of changes in land use (e.g. drainage/improvent and forestry) and neglect. This has left the county with a fragmented and disconnected distribution of this important habitat. Left alone without management, marshy grasslands undergo a rapid succession to birch and willow scrub which brings shade and dries the habitat so that it is no longer capable of supporting its key plant communities. They are rarely cut for hay and are best managed with a traditional grazing regime, e.g. with cattle. 

Good examples of species-rich marshy grassland in West Glamorgan can be found on Gower (e.g. Clyne Common, Fairwood Common and Welshmoor), north Swansea (Cadle Common), Cimla (Upper Cryddan Valley), the Dulais Valley and Pontardawe (Gwrhyd Meadows).

Species-rich marshy grasslands with Devil's-bit Scabious are crucial habitats for the Marsh Fritillary butterfly (Euphydryas aurinia) in south Wales.