9] VITAL IMPORTANCE TO MANKIND 281 



valueless but fast-growing and strangling Birches and Cottonwoods, 

 and, in water, the x^lgae which foul ships' bottoms and reservoirs, 

 clog irrigation ditches and navigation channels, and are troublesome 

 in many other ways. 



Further Consideration 



If it is felt that the resume of economic botany given in this chapter 

 is scarcely appropriate to a work on plant geography, however wide and 

 introductory this may be, it should be recalled that the essence of our 

 subject is distribution, and that not only the origin and supply but also 

 the availability where it is needed of a plant product (and hence its geo- 

 graphy) is of importance to Man and pertinent to our study. For Man 

 often ' shapes ' plants and their distribution even as they, in turn, largely 

 qualify his life and so limit the whereabouts and size of his populations. 



The importance of plants to mankind is stressed in the following works : 



F. O. Bower. Plants and Man (Macmillan, London, pp. xii -f- 365 



1925)- 



R. Good. Plants and Human Economics (Cambridge University Press, 

 Cambridge, Eng., pp. xii -)- 202 and additional maps, 1933). 



W. W. Bobbins & F. Ramaley. Plants Useful to Man, second edition 

 (Blakiston, Philadelphia, pp. ix -f 422, 1937). 



C. J. Hylander & O. B. Stanley. Plants and Man (Blakiston, Phila- 

 delphia, pp. X -I- 518, 1941). 



J. Hutchinson & R. Melville. The Story of Plants and their Uses to 

 Man (Gawthorn, London, pp. xv + 334, 1948). 



For further information about most economically important plants : 



A. F. Hill. Economic Botany, second edition (McGraw-Hill, New York 



etc., pp. xii + 560, 1952). 

 R. W. ScHERY. Plants for Man (Prentice-Hall, New York, pp. viii -\- 564, 



1952). 



E. E. Stanford. Economic Plants (Appleton-Century-Crofts, New York, 

 pp. xxiii + 571, 1934). 



K. H. W. Klages. Ecological Crop Geography (Macmillan, New York, 

 pp. xviii + 615, 1942). 



R. ZoN & W. N. Sparhawk. Forest Resources of the World (McGraw- 

 Hill, Ne.w York & London, 2 vols., pp. xiv + 1-493 ^^^ ^^^ + 495~ 



997. 1923)- 

 W. W. RoBBiNS. The Botany of Crop Plants, third edition (Blakiston, 



Philadelphia, pp. x + 639, 193 1). 



