208 MISCELLANEOUS USEFUL PLANTS 
careful crossing, hybridising and selection to ‘ improve ’ them, 
making the flowers more numerous, the inflorescences more 
crowded, the plants dwarf, the flowers double or of new 
colours, and so on. Others, e.g. Coleus, Caladium, Co- 
diaeum, are cultivated for their coloured or variegated 
foliage, or for their handsome leaves. 
Many trees are cultivated for ornament or shade, 
especially in the tropics, where many cultivations are carried 
on in a partially shaded condition. 
