Reproduction in Relation to Agriculture 229 



FIG. 144. Fiber from new varieties of long-fibered cotton at the right, obtained 

 by hybridizing and selecting progeny from the two forms producing the shorter 

 fibers at the left. The hybrid offspring excel both parents in the length of 



fiber produced. 







desirable plants. Weeds as a class are plants in which re- 

 production has reached the highest degree of efficiency. The 

 sequoia may stand for the culmination of vegetative efficiency, 

 the dandelion for efficiency in reproduction and dispersal. 

 The dandelion produces good seed without pollination ; if the 

 stem is cut, the plant develops numerous new sprouts; if 

 the root is cut into small pieces, each piece may sprout 

 from either end or from both ends at the same time. The 

 dandelion can thrive in a swamp, and it can withstand the 

 droughts of a sand plain. The sequoia still occupies the 

 comparatively small area in which it existed several thousand 

 years ago. It reproduces very slowly, and it is restricted to 

 a single habitat. The dandelion has in recent times spread 

 to all parts of the world, and it occurs in most habitats, 

 from the seashore to the alpine summits of mountains. In 

 other words, it becomes adjusted to many environments. 



