TREES FOR WATER CATCHMENT AREAS 169 



amount of warmth, and is intolerant of shade, the foliage 

 being so thin that it seldom prevents the growth of grass 

 underneath. It might be tried in warm sheltered spots in 

 the south of England, Wales, and south-eastern Ireland, 

 either grown as a standard over coppice on good soil, or 

 introduced in small groups in deciduous woods on alluvial 

 soil or rich loam. In raising seedlings, only nuts of 

 American origin should be used ; and as young plants are 

 difficult to transplant, on account of their long tap-roots, it 

 is better to sow the nuts in situ. See Quarterly Journal of 

 Forestry, ii. pp. 138 and 167 (1908); vii. pp. 28, 32, and 

 225 (1913); and ix. p. 67 (1915). 



Robinia Pseudacacia. — This American species, popularly 

 but erroneously called ' acacia,' grows to a large size in 

 parks in southern England. Its cultivation as a forest tree 

 in woods has been urged on account of the excellence of its 

 timber ; but successful plantations of Robinia are rare or 

 non-existent. The tree requires much light and space 

 during its whole life, and when overshadowed rapidly loses 

 vigour and declines. It carries a thin crown of foliage, 

 which is unable to suppress the grass beneath. It is easily 

 broken by wind, and suffers much in any exposed situation. 

 It is tender to spring and autumn frosts, and requires con- 

 siderable warmth in summer for its proper development. 

 Against these demerits may be set the inducement that it 

 thrives in poor sandy soils, provided these are deep. It, 

 however, only attains a large size on deep sandy loam. It 

 may be tried as a standard in coppice in the southern 

 counties of England ; but probably the best way of cultivat- 

 ing Robinia would be to plant it scattered as solitary trees 

 in birch woods on sandy heaths. Shelter would thus be 

 provided against the wind, while there would 'be enough 

 sunlight for it to develop. Amidst birch Robinia cleans its 

 stem perfectly, being often free from branches up to 30 feet 

 in fairly deep soil. It might also be introduced into chest- 

 nut plantations on sandy soil. It is easily raised from seed, 

 and young plants should be transplanted when a year old, 



