152 NATURE TEACHING. 



feeding on the trees of a neighbouring ' walk.' 

 The fruits of such plants are often green, incon- 

 spicuous, and unpleasantly flavoured whilst the 

 seeds are unripe but after they are ripe the 

 fruits are often brightly coloured, easily seen, 

 and sweet to the taste. Many of the fruits 

 of this class have been greatly altered in 

 character by cultivation and selection by man 

 who has increased the pleasant edible portion, 

 even to the suppression of the seeds, for 

 instance bananas, pine apple, seedless oranges, 

 etc. 



7. The ' mistletoe,' which has a fleshy 

 berry much eaten by birds, has an interesting 

 method of seed dispersal. Its seeds arc 

 extremely sticky, and when a bird eats the 

 fruit the seeds adhere to its bill. The bird, 

 sooner or later cleans its bill by rubbing it 

 against the bark of the tree on which it has 

 been feeding or of some other tree to which it 

 has since flown. The seeds stick, and after 

 germination pierce the bark and so establish 

 themselves. 'Mistletoe ' once introduced into 

 an orchard may thus rapidly spread from tree 

 to tree and become an extremely troublesome 

 pest. 



