The Fragrant orchids have been the subject of much molecular study in recent years, and as a result of the considerable differences revealed between them, the three British-growing varieties currently recognised as Gymnadenia conopsea (Chalk Fragrant-orchid), Gymnadenia borealis (Heath Fragrant-orchid) and Gymnadenia densiflora (Marsh Fragrant-orchid) may eventually be accepted as three distinct species. The third of these types, Marsh Fragrant-orchid, grows in alkaline marshes and is therefore more easily distinguishable by habitat if not by obvious morphological differences. The remaining types, Chalk Fragrant-orchid and Heath Fragrant-orchid are more difficult to tell apart: not only do they look very similar, but there are also numerous intermediate specimens between them adding to the confusion.
The Anglesey Fens National Nature Reserves in North Wales are a good place to see this orchid because they provide a rare habitat that suits it - marshy ground that is not so acid that they cannot survive. The reason for this special environment is that the fens are surrounded by limestone rocks which filter the water running into the marsh raising the alkaline levels of the substrate.
The Marsh Fragrant-orchid can grow up to 70cm in height and has a densely-packed flower spike which varies from light to dark pink.
Gymnadenia densiflora is more common in the south of the UK and only one site is known from the west of Scotland. It also occurs in many European countries.
The specimens above were photographed at Cors Bodeilio National Nature Reserve in the Anglesey Fens, North Wales in mid- June.