DEATH RATE OF SEEDLINGS 383 



smothered and to have its light cut off by the vege- 

 tation around it 



Plants producing small seeds, on the other hand, 

 have two great advantages. The seeds can be produced 

 in far greater numbers with an equal supply of food 

 from the parent plant, and they are much more readily 

 dispersed, so that there is more chance of many of 

 them reaching comparatively distant spots where they 

 :an germinate and establish themselves, and thus 

 the species has a better chance of wide distribution 

 md ultimate survival. The two most widely distributed 

 md numerous families of flowering plants, the grasses 

 Gramineae) and the composites (Compositae) , both have 

 nail one-seeded fruits, and distribution is often facili- 

 ited in the latter case by the pappus (p. 370). 

 Death Rate and Competition. The death rate of 

 jeds and seedlings in nature, like that of all young 

 ganisms, is enormous. Besides the large number of 

 ;eds which fall in places where they cannot germinate 

 tid the large number that are eaten by animals, many 

 jeds which do begin to germinate are killed at an early 

 :age by finding no suitable soil in which they can root, 

 y being smothered or cut off from light by other plants, 

 r by the attacks of fungi or small insects. At a rather 

 iter stage very many are eaten off by rodents or by 

 rowsing animals. No seedling of a woody plant can 

 arvive, for instance, in heavily pastured grassland, 

 erennial herbaceous plants like the grasses survive 

 i such land because of their underground and surface 

 loot systems, which possess buds that grow out as soon 

 3 the upper shoots are eaten off. 

 If we suppose an annual plant to produce only ten 

 :edlings a year, and all of these survive and them- 

 Ives produce seed, we should have in the twelfth 



