FLOWERS AND FRUITS 149 



crowded together that only a very few would live. Many 

 of the plants which are troublesome weeds are so owing 

 to their good methods of seed dispersal. In studying 

 the dispersal of seeds the uses of the different kinds of 

 seeds and fruits will be seen. 



Dispersal of Fruits and Seeds. 



There are four principal methods by which seeds 

 are distributed : (i) wind; (2) water; (3) animals ; the 

 seeds being carried either inside or outside the animal ; 

 (4) by some explosive apparatus. 



Wind. Many seeds for instance, those of the 

 common grasses are extremely small and light, so that 

 they readily float in the air. Some large seeds are 

 carried about in a similar manner, and these are often 

 provided with thin appendages of various kinds known 

 as " wings." Good examples of winged seeds are those 

 of the pines, whilst in the ash, elm, and maples the whole 

 fruit has a big wing and is blown about. Other wind- 

 borne fruits and seeds are provided with downy or silky 

 hairs which enable them to float; for instance, thistle, 

 dandelions, lettuce, willow-herbs, etc. 



The seeds of many plants lie at the bottom of dry 

 seed -cases (often open only at the top) and out of which 

 it looks extremely difficult for the seeds to get until the 

 seed-case decays. On a still day this is so, and no seeds 

 escape. When, however, there is a strong wind blowing, 

 the plants are shaken about and the seeds often thrown 

 or sprinkled to a considerable distance. It will be easily 

 understood that this is preferable to having the openings 

 at the bottom, for in the latter case the seeds would 



