58 



THE VEGETATIVE SHOOT 



number of thick, fleshy, scale-leaves, which overlap each other 



more or less com- 

 pletely. The whole 

 structure is practi- 

 cally a huge bud, 

 and in the axils of 

 some of its scales 

 are small, rudimen- 

 tary buds. Familiar ex- 

 amples are met with 

 in the onion, tulip, 

 lily, hyacinth, snow- 

 drop, and narcissus. 



The onion seedling, 

 figured on page 20, 

 develops several leaves 

 during summer, as 

 at A, Fig. 24, and 

 the plant swells at its 

 base and forms a bulb. 

 A section, as at B, 

 reveals its structure. 

 Tracing the leaves 

 from the green parts 

 downward, it is ob- 

 served that the bases, 

 especially of the inner 

 ones, are thickened, 

 and it is these leaf- 

 bases which form the 

 main mass of the bulb, 

 the stem (s) upon which 

 they grow being com- 

 paratively small. At 



B A 



Fig. 24. — A, Young onion plant; a remains of an 

 old leaf; c c younger leaves. 



Bj Longitudinal section of the same ; s short stem ; 

 b leaves and leaf-bases forming the chief part of the 

 bulb ; p growing point of stem. 



