CHAPTER VI 



SEEDS AND GERMINATION 



The seed contains a miniature plant, or embryo. The 

 embryo usually has three parts that have received 

 names : the stemlet, or caulicle ; the seed-leaf, or cotyledon 

 (usually I or 2); the bud, or plumule, lying between or 

 above the cotyledons. These parts are well 

 seen in the common bean (Fig. 15), particu- 

 larly when the seed has been soaked for a 

 few hours. One of the large cotyledons — 



Fig. 15. — Parts . . u ir »£ <-t, i, • u t 



OF THE Bean compnsmg half 01 the bean — is shown at 

 R, cotyledon; o, R. The cauliclc is at O. The plumule is 



mule -'^'j^!' first showuat^. The cotylcdons are attached 



""de- to the caulicle at F : this point may be taken 



as the first node or joint. 



The Number of Seed-leaves. — All plants having two 

 seed-leaves belong to the group called dicotyledons. Such 

 seeds in many cases split readily in halves, e.g. a bean. 

 Some plants have only one seed-leaf in a seed. They 

 form a group of plants called monocotyledons. Indian 

 corn is an example of a plant with only one seed-leaf : 

 a grain of corn does not split into halves as a bean does. 

 Seeds of the pine family contain more than two cotyledons, 

 but for our purposes they may be associated with the dicoty- 

 ledons, although really forming a different group. 



These two groups — the dicotyledons and the mono- 

 cotyledons — represent two great natural divisions of the 

 vegetable kingdom. The dicotyledons contain the woody 



