The soil under the Dorset heathland is very sandy; that is to say, made up of large granules rather than the finer grains found in clay or loam soils. As a result of this granular soil plants find it difficult to get a 'root hold'. Any nutrients get easily washed through the sand by rain and it makes it a very difficult environment for plants to grow in. The primary type of plants that are well able to cope with this hostile environment are the heathers.
The bell heather (Erica cinerea) comes out in August and the Purbeck heaths, in particular, become the most amazing colour purple emanating from the masses of this plant. Bell heather is the most common of the heathers in the Purbeck area giving way to ling further north and east. It dominates the drier areas of the heath and can be told from the other species by this distinct purple colouring, its two close relatives are much paler.