Area: 11.9 hectares.
Chyenhal Moor, situated in a poorly drained valley 3 km south west of Penzance, supports a diverse range of habitats including willow carr (the predominant vegetation type), heath, stream, pond, areas of Juncusvegetation and scrub. It is of particular interest as a locality of several rare plant species which are mainly associated with the wet heath areas. The site is underlain by coarsely porphyritic granite of the Land’s End peninsula. Drainage over the Moor is poor. The soils are mainly humic gleys with varying depths of overlying peat.
The often dense willow carr reaches a height of 5 metres and is dominated by grey willow Salix cinerea with the occasional goat willow Salix caprea. The ground flora includes lesser spearwort Ranunculus flammula, marsh thistle Cirsium palustre, soft rush Juncus effusus and yellow flag Iris pseudacorus. In wetter places, Sphagnum spp and other mosses are associated with purple moor-grass Molina caerulea, marsh pennywort Hydrocotyle vulgaris, creeping forget-me-not Myosotis secunda and water-mint Mentha aquatica. Small patches of wet heathy vegetation within the willow support such notable species as cornish moneywort Sibthorpia europaea, wavy-leaved St John’s wort Hypericum undulatum, and ivy-leaved bellflower Wahlenbergia hederacea. To the north is a more open heathy area where common gorse Ulex europaeus and heather Calluna vulgaris are dominant. The rare Dorset heath Erica ciliaris is found here, although it is recorded as being planted in 1934.
The pond in the southwest corner of the site is flanked by rush species dominated vegetation, with species such as sharp-flowered rush Juncus acutiflorus, purple moor-grass, ragged robin Lychnis flos-cuculi, water mint, marsh St John’s wort Hypericum elodes, bog pimpernel Anagallis tenella, and scaly male-fern Dryopteris affinis. Of particular note is pillwort Pilularia globulifera, a rare plant of wet heathland and acid pools. The overgrown pond to the southeast supports the rare unbranched bur-reed Sparganium emersum and ivy-leaved duckweed Lemna trisulca, a species which is exceptionally rare in Cornwall. Star sedge Carex echinata, glaucous sedge Carex flacca and heath spotted orchid Dactylorhiza maculata occur in the more open wet heathy habitats.
Of the seven dragonfly species recorded at this site, broad-bodied chaser Libellula depressa and four-spotted chaser L. quadrimaculata are of particular interest.
Chyenhal Moor has been a well known location for rare plant species since John Ralfs’ (1807–1890) discoveries here.
In addition to the plants noted above, those unconfirmed in recent years include three-lobed crowfoot Ranunculus tripartitus, coral necklace Illecebrum verticillatum and the dwarf rush Juncus capitatus. The site is now heavily overgrown and it is hoped that sympathetic management will encourage the return of these additional rare plant species.