NATURE'S OFFERINGS FOR SPRING PLANTING 199 



In all nurseries, wild and tame, plants are propagated in a 

 variety of ways. Most trees are grown from seeds; the 

 .dominant species of our forests are increased in hardly any 

 other way; but most shrubs and perennial herbs, while they 

 produce seeds abundantly, have other modes of increase. 

 They produce new plants by offsets, suckers, stolons, layers, 

 etc. New plants thus formed are grown and nurtured under 

 the shelter of the old ones. 



The cockle-mint of our brook-sides, (Physostegiavirginiana.) 

 (fig. 79) is a plant well habituated to this mode of increase. 

 It produces annual herbaceous stems that bear four-ranked 

 columns of beautiful bright pink flowers, and that are usually 

 followed by a heavy crop of seeds. But the seeds are minute, 

 and the seedlings are a bit slow about getting started. In 

 the everywhere crowded brook-side thickets, their chance for 

 completing development is indeed a very rare one. Did 

 this plant depend on holding its place by new development 

 from seeds every year, doubtless it would quickly disappear. 



But it has other resources. From the base of each flower- 

 ing stem, a number of offsets are produced as underground- 

 branches. Each of these is equipped with an abundance of 

 roots, with a store of reserve food material (thickening it 

 apically), with a big apical stem-bud, and with a few green 

 leaves at the surface of the ground, all ready for growth when 

 spring breaks. As compared with a puny seedling, it is 

 already a strong and well-established plant. The provision 

 it makes for future needs extends yet farther ahead. On the 

 sides of each offset, there are produced a number of long 

 naked buds, that will grow out into new offset branches 

 another season, and rise on stems and bloom and bear and 

 die the summer thereafter. 



In contrast with reproduction by means of seeds, the 

 increase by this method is slow but sure. Plants of this sort 

 hold their place in the world by continuous occupancy of it. 



