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. Im 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 Jowrnal 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, 
