26 



OnOANOOBAPHY. 



typical form ; besides these there are many modified forms, 

 some of which have departed so far from the type that 

 their true nature can be understood 

 only when we see all the intermediate 

 forms or gradations connecting the 

 two extremes. Such are Cotyledons, 

 Scales, Spines, Tendrils, Pitchers, 

 and Fly-traps. 



26. The two halves into which a 

 Pea, Bean, etc., readily divide are 

 ^. called the cotyledons (Gr. kotvia, 

 cup), or seed-leaves (Fig 22, cot). 

 If they be observed, in case of the 

 Pumpkin and certain other plants, 

 some time after germination they 

 will be found to have changed their 

 ': shape somewhat and become green, 

 like ordinary leaves. As a rule, 

 however, the cotyledons are simply 

 to nourish the plantlet during germination. In the bulb- 

 scales is stored up food for the early growth of the plant 

 the following season. This nourishment is consumed, in 

 such bulbous plants as the Hyacinth, etc., 

 by the production of flowers in advance 

 of the leaves. 



27. The leaves of underground stems 

 are generally reduced to mere scales. 

 These bud-scales, which protect the tender 

 parts within, are modified leaves. A 

 gradual transition between them and the 



Fig. 22. Different stages in the germination of the Bean : cat, cotyledons ; r, 

 tadide ; //, plumule. Fig. 23. Spines, which are modified leaves, of the Barberry. 



