This section is from the book "British Wild Flowers - In Their Natural Haunts Vol5-6", by A. R. Horwood. Also available from Amazon: A British Wild Flowers In Their Natural Haunts.
A feature that may be pointed out in studying the conditions of heath vegetation is the association of commonland with a certain type of soil which is suitable for the latter, and which is largely colonized by Furze, and the plants that usually grow with it.
Commonland is not only land that has been devoted to the general needs of the community, but has other characteristics which cause it to be left uncultivated and unenclosed. It is usually poor, sandy, or gravelly soil, which is suitable only for grazing. Commonland is also largely developed upon the slopes or summits of hills, where the ground is littered with stones, and unfit for cultivation. In this way it is especially favourable to the type of heath vegetation where Ling, Furze, Pine, and the usual ericetal plants occur.
Furze frequently grows on the sides of paths, where also ants may be found. Indeed, it is an interesting fact that ants to a great extent disperse the Gorse, finding nutriment in the elaiosomes or oily appendages of the seeds. Amongst the Furze will be found many plants common to the grass heath, and a common may, in fact, be made up largely of grass heath.