98 Water 



case exposing themselves as little as possible. Their 

 leaves, too, are for the most part narrow, and so 

 scantily distributed over the branches that an Aus- 

 tralian forest has none of the deep shade which the 

 word naturally suggests to us. 



But when the eucalyptus is transported to other 

 lands, where it has plenty of deep, rich soil, and 

 moisture in abundance, then it puts on more foliage, 

 showing that it was only the dry heat of its native 

 climate which made it so sparing of its leaves. 



Most of the many species of acacia found in 

 Australia go even a step beyond the eucalyptus in the 

 way of economizing their foliage, and give up having 

 any true leaves at all as soon as they are full-grown. 

 They keep their leaf-stalks indeed, but there are no 

 leaves at the end of them, and instead there are 

 ' wings,' or narrow, leaf-like margins, growing out 

 from each side of the stalks. Even these 'wings' do 

 not venture to face the sun, but turn their edges to 

 earth and sky. 



Acacias are especially the trees of deserts ; they are, 

 indeed, the only timber-trees of the Arabian Desert, 

 and they abound in Africa, as also in Australia. But 

 wherever they grow they are characterized by the 

 lightness of their foliage ; and of the Australian species, 

 which number something under three hundred, two 

 hundred and seventy drop their leaves altogether when 

 they are grown up, and merely flatten out their leaf- 

 stalks as described. 



None of the Cactus family which are natives of 

 the hot, dry regions of America, North, South, and 

 Central make any attempt at having leaves or even 

 ' wings/ but their stems are flattened out and do 



