Many species are linked to a favoured habitat and that usually depends on the chemical composition and moisture level of the soil being suited to the plant's requirements. Some are not just linked to favoured habitat types, some are actual indicators of a specific habitat type. So it is with the purple moor grass (Molinia caerulea). Purple moor grass and rush pasture is a recognised habitat type that obviously features purple more grass and rushes (usually soft rush) mixed in. This habitat often features the meadow thistle, devil's-bit scabious and heath and common spotted orchid as insects such as the marsh fritillary butterfly and the narrow bordered bee hawk moth. This habitat type occurs on heavy, moist, peaty or acidic clay soils and it occurs in various places in Dorset although it is by no means as common as it once was due to extensive draining and improvement for agriculture of the sites.
Purple moor grass occurs in may other situations too and is especially frequent on the Dorset heaths, especially the wetter areas but not where the ground is frequent. It grows in small tufts and also in large tussocks and various stages in between. Tall stems grow from the basal leaves and from July through until September purple 'flowers' appear at the top of the stems. Where there is a lot of this grass growing together it can be a lovely site as the summer breeze sends ripples through these grass stems. Once over, the flowers turn brown and can be seen for some considerable time in to the winter.Molinia caerulea: the purple moor grass