Habits of Growth, 69 



are infested by each particular kind of weed, 

 and the power which the various kinds pos- 

 sess of maintaining themselves in perma- 

 nent pastures and waste places. 



Some annuals, such as ragweed, bear 

 seeds in almost countless numbers, whereas 

 the number of seeds produced by creeping 

 perennials is usually not very large. The 

 diversion of the energies of creeping peren- 

 nials from seed-bearing to increase by 

 means of their root-stocks is, therefore, so 

 far unfavorable to their reproduction that 

 the excess of seed production in annuals 

 not infrequently more than counterbalances 

 the advantage gained by creeping perennials 

 by reason of the dual powers of propaga- 

 tion which they possess. Moreover, the vital- 

 ity of the seeds of some sorts of annual 

 weeds, as those of wild mustard, is so great 

 that they seem to be able to retain their abil- 

 ity to grow for a much longer period than 

 the seeds of creeping perennials. Again, 

 when the seeds of an annual or biennial 

 weed are transported from place to place by 

 water, or by animals, they are given an 

 advantage which goes far to match the 

 more dangerous powers possessed by the 

 seeds of some perennial weeds, such as the 



