Where soils are normally wet, they can develop either as marshes, on flatter ground, or flushes, where the ground slopes.
Marshy grasslands are very similar to other types of grassland and wetland but occur in wet hollows and next to streams and do have typical wetland herbs, unlike acidic and neutral grasslands which usually are species-poor.
Where calcium enriches the soil, plants such as grass-of-Parnassus and bird’s-eye primrose are found. The acid areas are less interesting but some characteristic species are found, for instance marsh pennywort.
Greenfield Meadow, at the head of Wharfedale, contains a tall fen with locally dominant tufted hair-grass, common knapweed, meadowsweet, and soft rush, lady’s mantle, marsh marigold, water avens, bogbean, marsh valerian, and marsh violet. There are also species-rich calcareous flushes dominated by long-stalked yellow-sedge and carnation sedge. Common twayblade, grass-of-Parnassus, marsh lousewort and common butterwort make an interesting association. The area is also known as a blackcock lek.
At Moss End, at Oughtershaw, there are a number of base-rich flushes, with bird’s-eye primrose, marsh hawk’s-beard, marsh valerian, common butterwort and a variety of sedges. The herb-rich grassland in which the flushes appear has blue moor-grass, wild thyme and salad burnet, with orchids, creeping willow, kidney vetch, flat-sedge and broad-leaved cottongrass.
Above Kettlewell there are many places where lime-rich water flushes the soil and purple moor-grass, the nationally scarce bird’s-eye primrose, butterwort, grass-of-Parnassus and marsh valerian can be found. Where damp areas have developed a peaty covering black bog-rush, marsh lousewort, broad-leaved cottongrass and northern marsh-orchid grow.
The calcareous flushes in the Malham-Arncliffe area have a number of uncommon bryophytes including Catoscopium nigritum and Meesia uliginosa with Orthothecium rufescens on damp limestone cliffs. Along the wood/pasture boundary of Scoska Wood are flushes with orchids, broad-leaved cotton-grass, grass-of-Parnassus, marsh arrowgrass, marsh valerian and bird’s-eye primrose.
Along Pen-y-ghent Gill are numerous flushes with marsh arrowgrass, bird’s-eye primrose, grass-of-Parnassus, few-flowered spikerush and scurvy-grass.
A particularly rich flush is to be found at Kilnsey, where a fen is dissected by springs from the limestone. To the centre there is a tussocky community of purple moor-grass, black bog-rush and various rushes, with blue moor-grass and a number of sedges including carnation sedge, long-stalked yellow sedge and tawny sedge. Flowering plants include the local narrow-leaved marsh orchid, marsh helleborine, early marsh orchid, broadleaved cotton-grass, lesser club-moss, pepper saxifrage, grass-of-Parnassus and bird’s-eye primrose. Around this is a tall-herb fen community with water avens, meadowsweet, great burnet, devil’s-bit scabious, wild angelica and marsh valerian.
Flushes on the acidic Barden and Blubberhouses moors are home to bog pimpernel and bog pondweed. The nationally scarce species, pale forget-me-not occurs in a number of places.
Do not assume that sites mentioned here have public access. Please use only public footpaths or ask permission for access. Conservation of our wild heritage depends on the goodwill of landholders – please don’t abuse it!