250 Seed-Scattering 



Where seedlings are crowded together there must 

 always be a struggle as to which shall survive, but it is 

 much more severe where all are of the same sort. 

 Where they are mixed, some will have advantages. 

 They may be larger and stronger, or they may be 

 better fitted for the soil and situation. Whatever the 

 advantage may be, those possessing it will speedily 

 overpower their less fortunate rivals, and then, having 

 secured sufficient elbow-room, will grow up strong and 

 healthy. 



Plants of different species, when crowded together, 

 are better off in another respect, for they do not all 

 want precisely the same amount of the various mineral 

 foods, and so there is more for all. For this reason it 

 is a very usual thing to sow a grass-field with seed of 

 different species; and the greater the variety, the 

 heavier the crop of hay, because the plants have had 

 a better opportunity of obtaining food. 



On this account, therefore, as well as that they may 

 have change of air, it is well for seeds that they should 

 be scattered, or otherwise dispersed. But there are 

 other reasons still. 



Some plants need shelter, and are killed by sudden 

 exposure. If they had no means of dispersing their 

 seeds, not only they, the parents, but their whole 

 progeny, might be exterminated by the removal of 

 trees, etc. Or again, by the draining of a pond or 

 drying up of a brook, plants needing much moisture 

 might be killed out of a neighbourhood, if all their 

 seeds dropped close round them, while they might 

 continue to flourish if they were able to migrate the 

 distance of only a few yards. 



In some cases, too, the parent so exhausts the soil, 



