86 



ROUND THE YEAR 



every fresh case has its own peculiar features. The 

 Poplar, the Bullrush and the Willow-herb (so named 

 from the shape of the leaves) are curiously like the 

 Willow in the mode of dispersal of the 

 seeds. 



The catkin is a form of inflorescence 

 particularly well-suited to wind-fertili- 

 sation. The pollen-grains are formed in 

 vast numbers within the crowded flowers 

 of the long catkins ; they are easily 

 shaken out of these dangling tassels, 

 wafted by the wind to great distances, 

 and lodged on the branching styles of 

 the female cones. The Willow gets 

 help from Insects, especially Bees, which 

 visit its nectar-bearing flowers on bright 

 days. Willows will set their seeds 

 though there is no male plant within a 

 mile. 



Why do catkins appear so early, be- 

 fore the leaves are out ? It may be 

 that the leaves would interfere with the 

 dispersal of the pollen by wind. They would in- 

 evitably catch much of the pollen wafted to or from 

 the tree, so that there is a distinct advantage in 

 getting the flowers fertilised before the leaves 

 appear. 



The pollen of Willow does not depend upon 

 wafting by the wind, yet the Willow flowers before 

 it comes into leaf. Yes, and it secures two consider- 

 able advantages thereby. Its catkins are far more 

 conspicuous on bare boughs and the Bees are very 



FIG. 30. Ripe 

 cone of Birch. 



