PLANTS. 83 



these plants belong, is the seed pod. The bean or 

 pea pod is in reality a transformed leaf. When a 

 pod is broken open, laid out flat, and the seeds 

 taken out, it resembles a leaf very much. The 

 long^tough fiber along the back of the pod cor- 

 responds to the mid-vein of the leaf, and the line 

 along the front of the pod is the union of its two 

 margins. The fibers of green pods are called 

 strings and must be removed before the pods are 

 cooked for food. 



Beans and peas are good examples of the two- 

 cotyledonous plants. That is, the seeds are in two 

 parts, and in germination these two halves are 

 lifted into the air above the ground to act both as 

 leaves and a storehouse of supply, till the plants 

 have enough roots and leaves to make a living for 

 themselves. It will be noticed that the two cotyle- 

 dons, or halves of the seed, turn green as soon as 

 they reach the light and air, which means that 

 they are endowed with chlorophyl and can manufac- 

 ture protoplasm as well as supply it ready made. 

 As soon as true leaves are developed, the cotyle- 

 dons are absorbed by the plant and fall into disuse. 



Beans and peas grow rapidly, requiring but from 

 six to ten weeks for growth and maturity; hence, 

 they are planted from early spring till the middle 

 of summer. They are annual plants and die away, 

 root and stalk, as soon as the seeds ripen. 



The seeds germinate and spring up in a day or 

 two when planted in warm, moist soil. They need 

 but a thin covering of earth for germination. 



