260 



TYPICAL FLOWERING PLANTS 



Figure 253. — Photograph of Bean 

 and Pea. 



and the stem which supports the leaves, flowers, and 



pods. Each of these parts is called an organ, and each 



does a given work. While we are learning how the bean 



uses these organs, we 

 shall compare them with 

 similar organs in other 

 flowering plants, and in 

 this way come to under- 

 stand how all plants of 

 this kind live. 



200. The Bean Seed. — 

 The bean seed discussed 

 in this study is the 

 familiar dry bean, white 

 or red in color. This 



seed contains the embryo or young plant which consists 



of three important parts, all inclosed in the seed coat 



(testa). These parts are : (1) the 



small stem, the hypocotyl (hy-po-kot p l: 



Greek, hypo, beneath ; kotyle, cavity) ; 



(2) the seed bud, the plumule (plum'ul : 



Latin, plumula, feather); (3) the seed 



leaves, the cotyledons (kot-y-le'don: 



Greek, kotyledon, socket). See Figures 



253 and 254. 



Every bean is attached at a definite 



point to the pod in which it grows, and 



a scar, called the hilum (hl'lum: Latin, 



hilum, a little body), shows where the Compare with Figure 



point of attachment was. Through this 



hilum enters all the food material which makes the bean 



seed. The testa or coat of the bean is the hard outer 



layer, and beneath this may sometimes be seen a delicate 



inner layer, called integument These two layers of the 



P 3 phe 



Micropyle 



Plumule 



Hilum 



JAJ /''Testa 

 Cotyledon 



Figure 254. — Parts 

 of Bean Seed. 



