40 



HORTICULTURE FOR SCHOOLS 



An understanding of these parts can best be obtained by 

 studying certain of the larger seeds under a magnifying glass. 

 Before examination, the seeds should be boiled for fifteen or 

 twenty minutes or soaked in water over night. Beans, peas, 

 corn, and pumpkin seeds are especially convenient for study. 



50. The pea (Fig. 

 20) . Several marks are 

 visible on the outer sur- 

 face of the pea. A large 

 \ scar, called the hilum, 



PARJ PRODUCED marks the point of at- 

 FROMxPLUMULE , , ,, , 



tachment to the pod. 

 At one side of the hilum 

 is a little hole known as 

 the micropyle. This is 

 the point where the 

 pollen-tube entered in 

 the fertilization of the 

 ovule. These marks be- 

 long to the coat of the 

 seed, for if the coat 

 (testa) is removed the 

 marks come with it. 

 The removal of the coat 

 disci oses two thick parts 

 of the seed (cotyledons), 

 commonly called the two 



PRODUfcED 

 CAULICLE 



FIG. 20. The young pea plant. Unlike the bean halves of the pea. The 

 the cotyledons stay in the ground. Notice the 

 plumule, and the roots developing from the 

 caulicle. 



cotyledons contain a 

 large quantity of stored 

 food material on which the growing plantlet lives until it 

 develops roots to take up nourishment from the soil and a 

 foliage system to manufacture plant-food. Attached near 

 its middle to the cotyledons is a little curved body (the 

 embryo of the pea), of which one end (trie caulicle) will 



