108 PRINCIPLES OF PLANT CULTURE 



Plants under glass usually thrive better after midwinter 

 than before, and the most favorable time to plant seeds 

 of greenhouse plants is toward the close of the natural 

 rest-period. 



179. The round of plant life has now been traced, from 

 the first swelling of the planted seed, through the develop- 

 ment of the embryo into the plantlet, the penetration of 

 the root into the dark and damp soil cavities, the absorp- 

 tion and conduction of water with its food materials in 

 solution, cooperating with the sunlight and carbonic acid 

 in the mysterious laboratory of the leaf, in building up 

 the plant body into node and internode, leaf, bud, branch, 

 flower, fruit and seed ; through growth, decline, leaf fall 

 and winter sleep, to the renewed vigor of another spring- 

 time. 



In our study of the round of plant life, we have as- 

 sumed the environment to be favorable. But in the prac- 

 tical culture of plants, we are constantly meeting with 

 adverse conditions of environment. Talent for plant cul- 

 ture lies in the ability to discern these adverse conditions 

 by the appearance of the plant, and in knowing how to 

 correct them. We will, therefore, next consider the plant 

 as affected by unfavorable conditions of environment. 



The following books are recommended for reading in 

 connection with the preceding chapter : " How Plants 

 Grow," Gray ; " Outlines of Botany," Leavitt ; " Lessons 

 with Plants," Bailey; "Plant Anatomy," Stevens; 

 "The Soil," King; "The Fertility of the Land," 

 Roberts; "Plant Physiology," Duggar; "Experiments 

 with Plants," Osterhout. 



