COTYLEDONS. 



617 



we shall liave repeated occasion to refer. The Feather-grass at once claims our 

 attention in the drawing by its tufts of white feathery streamers swinging in 

 the wind. These structures are awns, which have elongated in this remarkable 

 manner since the time of flowering of the grass. 



The glume, which is crowned with the feather-like awn, together with a second 

 short glume, destitute of awn, incloses the small fruit. As .soon as it is ripe, the 

 fruit, wrapped in its glumes, becomes detached; the first breeze carries it off and 

 blows it like down over the steppe. The long feathery awn arising from the 

 glume has thus, in the first instance, the significance of a flying apparatus, like 

 so many of the feathery or wing -shaped structures which beset or envelop seeds 

 and fruits. It effects the distribution of the feather-grass in question over wide 



Fig. 140. — Anchoring of the W.atcr-eliestnut (Tfapa). 



tracts of country. But after the awn has become stranded somewhere on the 

 .soil of the steppes, it has yet another function to perform. 



Let us suppose that a feather-grass fruit has fallen on to the bare earth, as 

 in the illustration on p. 619; that part containing the fruit inclosed in the glume, 

 as it is the heaviest, will obviously come first into contact with the ground; and 

 since the tip of this portion is hard and sharply pointed, the sti-anded fruit often 

 sticks in the ground immediately upon alighting (fig. 147 ^). Should it fall obliquely, 

 the tip will penetrate into the ground by the continued twisting of the long 

 feather waving in the air. This first penetration is materially favoured by the 

 fact that the point is bent a little obliquely towards one side. 



When once the point has penetrated into the soil, the other portions of the 

 glume surrounding the fruit soon follow, owing to the action of the following 

 contrivance. Close above the point of the enveloping glume are inserted up- 

 wardly-directed hairs which are at once elastic, flexible, and yet stiff. As long 

 as these stiff' hairs lie close they offer no resistance to the penetration of the 

 glume into the soil, and some of them are actually embedded in the soil even at 

 the first penetration of the point. Now if the fruit as it pierces the ground be 

 inclined to one side, by some pressure operating ever so lightly from aljove, then 

 the hairs on that side are pi'essed still more closely against the glume, while those 



