CHAPTER IV 



FURTHER GROWTH AND DURATION OF PLANTS 



Bv the time the plant has germmated, that is, has unfolded the 

 parts formed in the embryo, and has used up the stored food, 

 the root, by means of the root-hairs, has become closely attached 

 to the soil. New roots are sent out with their root-hairs, 

 and the plant is able to get its own food material, partly from 

 the soil through the roots and partly from the air by means of 

 the leaves. While the embryo was unfolding the plant was not 

 increasing in dry weight, but by the time the first new leaves 

 are forming the plant is beginning to add to its weight ; growth 

 has really begun. 



In none of the seeds studied were the cotyledons and 

 plumule similar in appearance. In the bean, after the two 

 plumule leaves, but one leaf unfolds at a time. There appear 

 to be three, but they are all borne on one leaf-stalk. Notice 

 the little cushion at the base of each part. Look for the 

 cushion in the Oxalis leaf. When they are inflated with sap, the 

 leaflets bend down to sleep. Look for them in clover. Are 

 they in the same position ? Do clover leaves lie down to go 

 to sleep ? Do bean leaves go to sleep ? 



One pupil kept her bean plant carefully watered. After 

 awhile it bore branches. Where did they start? One day 

 a white blossom was reported ; others followed. They were 

 short-lived, the pretty white part fell, and it was feared the plant 

 would die. But in the centre of each flower a pod came. 

 Seeds appeared in the pods, and in each seed a new bean life 

 was formed. When the pods ripened, they split open, and the 

 seeds fell out. Then care and watching no longer availed. 

 The plant's lifework was done. It had borne fruit \ then it 



