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. 
Thecockle-mint of our brook-sides, (Physostegia virginiana.) 
(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 area 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. 
