138 THE NATUME AND WOBK OF PLANTS 



which finally lean over with their tips touching 

 the ground. Roots are formed at this point, and 

 the growth of leaves and a new main stem quickly 

 follows, making a new individual. 



190. Dissemination or spreading of the plant by 

 vegetative propagation. — In all of the above methods 

 by which new individuals are formed from portions 

 of the body of a parent plant, the new specimen 

 finds a foothold a greater or less distance from the 

 parent. Each successive set of new plants is still 

 farther away from the starting point, and it is to be 

 seen that any species might travel considerable dis- 

 tances by such seemingly slow methods. Thus some 

 of the young plants formed by the runners of a 

 strawberry will be five feet from the parent, and as 

 these quickly give rise to similar runners the species 

 would travel across a large meadow in a few years. 



191. Gemmce. — If the upper surfaces of flat 

 fronds of Marcliantia or Lunularia are examined, 

 small circular or crescent-shaped receptacles will be 

 seen containing a number of globose masses of green 

 tissue either loose or easily detached. These are 

 the portions of its body devised to reproduce the 

 species vegetatively, and are termed gemmce. If 



