634 Floristik, Geographie, S5^stematik etc. 



above, each is described in detail and the floristic composition of 

 each type is given. The Factors of importance in determining the 

 distribution of the woodland associations in the district are the che- 

 mical nature of the soil. the depth of the soil, and the altitude of 

 the woodland site. The variations of Vegetation within the woods, 

 due to local wetness or dryness. the character of the humus, etc. 

 receive special attention. Plantations are excluded from the group 

 of natural and semi-natural woods, and are briefly dealt with amongst 

 the culture associations. Scrub associations (p. 88—102) occupy an 

 important place in the area; their origin is considered and most of 

 them are regarded as retrogressive stages of the woodlands, com- 

 parative tables show the flora of scrub on sandstones, shale slopes 

 and limestone slopes. Grassland associations (p. 103—133) occur in 

 general on the slopes within the zonal limits of woodland and scrub, 

 or at higher altitudes on sites formerly covered with peat. The 

 siliceous grassland is characterised by heat-loving or humus-loving 

 species; two extremes are recognised, Nardus and Molinia, the 

 former including facies of Ulex, Pteris, Jiincus effusus, Agrostis 

 vulgaris, and Deschampsia ßexiiosa. Calcareous grassland includes 

 a group of associations characterised by lime-loving species, a com- 

 parative table shows these. The position assigned to these grass- 

 lands is expressed diagrammatically: 



Plant formation of 

 siliceous soils 



Plant formation of 

 calcareous soils 



Short chapters are given to associations of rocks and screes 

 (p. 135—143) and to marsh and aquatic associations (p. 144 — 162;. 

 The lists show the species, including hepatics and mosses, of sand- 

 stone and calcareous rocks and waters. The moorland associations 

 (p. 163 — 198), so well represented in the district, are described, and 

 special consideration is given to the factors relating to the distri- 

 bution of the moorland types, and to the subject of changes resul- 

 ting from retrogression. The culture associations (p. 199—213) include 

 farmland and plantations of trees. A useful appendix shows in a 

 Condensed and graphic form the plant communities ofthe area. and 

 their relationship. A second appendix tabulates the plant formations 

 and associations recognised in Britain, with distinguishing names, 

 e. g. Lemneta, Qiiercetum sessiHßorae, Calliinetiini vulgaris. There 

 is also a very füll bibliography. The illustrations include about 30 

 photographs of Vegetation well reproduced, and most of them as 

 nearly perfect pictures as black and white can attain. Useful illustra- 

 tive diagrams have also been introduced. The publication of this 

 memoir on a district well-known to botanists and others is a \vr-!- 

 come addition, and as indicated the treatment gives a more th;in 

 local interest so that it ma}^ be grouped amongst British text-books 

 on Vegetation studies. W. G. Smith. 



