The climatic and edaphic conditions are a low rainfall, a deep coarse dry sterile soil, low lime content, a low content of soluble minerals, and a tendency to the formation of acid humus, and of thin peat, accompanied by the leaching of the soil, which lead to the development of pan, involving a subsequent change in the vegetation. The dry oakwood consociation includes the natural and semi-natural oakwoods of Sherwood Forest in which Quercus robur and Q. sessiliflora, singly or together, are locally dominant. The woods conform to type, but the shrub layer is so poor in individuals as well as in species that it is almost non-existent, and, as a light absorbing layer, the stratum of Pteridium comes next to the tree canopy. The majority of the herbaceous spp. belong to the grass-heath association, and are abundant in open and marginal situations only. The real ground flora of the dry oakwood is scanty almost to the point of extinction, and it is shown that the absence of small geophytes and carpet plants is largely due to the slow rate of decay leading to the accumulation of loose dry humus, a factor also affecting the invasion of the oakwood by the heathy ground flora. The scrub association occurs principally by the waysides and on the commons and warrens, where it frequently develops into a progressive Ulicetum. The grass-heath association arises in various ways, chiefly by the degeneration of oakwood, and by the colonisation of the waysides and of land which is allowed to pass out of cultivation. Its most characteristic consociation is a closed Deschamp-sietum flexuosae, which has a considerable degree of stability, but ultimately passes into heath. The typical oak-birch heath of the south of England appears to be absent from Sherwood, the succession here being rather the replacement of the oakwood ground flora by Deschampsietum and not directly by Calluna and other true heath spp. The Callunetum occupies the extensive "wastes" of Rufford and Clipstone Forests, and is also abundant on wayside habitats. Whilst the heaths are of great age, they are not considered to be primitive, but as an edaphic succession following the degeneration of oakwood. There is no evidence of Pinus sylvestris spreading spontaneously in this area. The wet heath association is developed in damp hollows where the ground water lies near the surface, and is very restricted in extent.