21 6 Introduction to Botany. 



successfully in competition with other plants. The acorns, 

 which, in spite of their astringent taste, are palatable to 

 many nut-loving animals, are often carried away by them ; 

 and they are also stored by woodpeckers for the sake of 

 the insect larvae which frequently occur in them. On 

 account of their bulk and weight, the acorns are doubtless 

 occasionally dropped to the ground, and eventually suc- 

 ceed in becoming oak trees. 



Hooks, barbs, and sticky glandular hairs for clinging to 

 passing animals are frequently found on the fruits of many 

 families of plants (see h,j, k, in, and c, Fig. 127). Every 

 one is familiar with the fruits of the cocklebur and burdock, 

 which cling in great numbers to the tails and legs of cattle 

 and horses ; and the clinging qualities of the fruits of black 

 snakeroot, beggar-ticks, and bur-grass are too familiar to 

 need more than passing mention. In Mentzelia, the leaves, 

 stems, and fruits, are covered with anchor-like hairs which 

 become fastened to garments or to animals so tenaciously 

 that large portions of the plant may be broken off and 

 carried away at once. 



149. Dispersion by Water. — The nut-like fruits of the 

 yellow water lily, Nelnnibo bitea, are borne in top-shaped 

 receptacles which are at first upright, but, as the fruits 

 ripen, bend downward so that the nuts drop out or are 

 shaken out by the wind, and sink at once to the bottom of 

 the water (Fig. 69). Later in the season the receptacles 

 break away from their dry stalks and float about on the 

 water, carrying with them the few nuts which are still held 

 captive. In this way a considerable distance from the 

 parent plant may have been traversed by the time the re- 

 ceptacles have become sufficiently softened to set the 

 remaining nuts free. 



The fruits and seeds of many genera of water and 



