CHAPTER XXIIl 

 GERMINATION 



305. THE SEED.— We have found (259) that by the pro- 

 cess of fertilization a seed is formed. The seed contains a 

 miniature plant or embryo. The embryo usually has three 

 parts which have received names: the little steralet or 

 caulicle; the seed-leaf or cotyledon (usually 1 or 2) ; tlie 

 bud or plumule lying between or above the cotyledons. 

 These parts are well seen in the common bean (Fig. 282), 



particularly when the seed has been soaked 

 for a few hours. One of the large cotyledons 

 — comprising half of the bean — is shown at r. 

 The caulicle is at c. The plumule is at a. 

 bean*^r,cotyie^ The cotyledons are attached to the caulicle 

 a^'piuinuye'^ ^ at /: tMs poitit IS the first node, and the 

 hrstno e. plumule IS ttt the second node. 



306. Every seed is provided with food, to support the 

 germinating plant. Commonly this food is starch. Tlie 

 food may be stored in the cotyledons, as in bean, pea, 

 squash; or outside the cotyledons, as in castor bean, pine, 

 Indian corn. When the food is around the embryo, it is 

 usually called endosperm. 



307. The embryo and endosperm are inclosed within a 

 covering made of two or more la3'ers and known as the 

 seed-coats. Over the point of the caulicle is a minute hole 

 or a thin place in the coats known as the micropyle. 

 This is the point at which the pollen -tube entered the 

 forming ovule and through which the caulicle breaks in 

 germination. The micropyle is shown at m in Fig. 283. 

 The scar where the seed broke from its funiculus or stalk 



(164) 



