144 THE STORY OF THE PLANTS. 



numerous bright yellow stamens of the males. 

 It is this that causes them to be used for 

 " palm " in churches on Palm Sunday. The 

 male and female catkins grow on different trees, 

 so as to ensure cross-fertilisation, and the dif- 

 ference between the two forms is greater per- 

 haps than in almost any other plant, the males 

 consisting of two showy stamens behind a 

 winged scale, and the females of a peculiar 

 woolly-looking ovary. 



Even more important is the great wind-ferti- 

 lised group of the grasses, to which belong by 

 far the most useful food-plants of man, such as 

 wheat, rice, barley, Indian corn, and millet. 



Grasses are for the most part plants of the 

 open wind-swept plains, and they seem natu- 

 rally to take therefore to wind-fertilisation. 

 Their flowers are generally small, clustered into 

 light spikes or waving panicles, and hung out 

 freely to the breeze on slender and very movable 

 stems, so as to yield their pollen to every breath 

 of air that passes. Moreover, the plants as a 

 whole are slender and waving, so that they bend 

 before the breeze in the mass, as one often sees 

 in a meadow or cornfield. Thus the grasses are 

 almost the pure type of wind-fertilised plants; 

 certainly they have carried further than any 

 other race the devices which render wind- 

 fertilisation more certain. 



On this account they are so complicated and 

 varied that I will not attempt to describe them 

 in detail. I will only say that grasses are 

 | descendants of the threefold flowers, and in all 

 probability degenerate lilies. Their individual 



