26 



OnOANOGRAPnY. 



typical form ; besides these there are many modified forms, 



some of which have departed so far from the type that 

 their true nature cau 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. Icotula, 

 cup), or seed-leaves (Fig 22, co€). 

 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 hulb- 



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



the following season. This nourishmeut 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 b.etween them and the 



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

 radicle ; ^/, plumule. Fig. 23. SpineSj wliicli arc modified leaves, of the Barberry. 



