60 Elementary Work in Botany. 



or ten inches, and that of the nearly equal leaflets about 

 three inches.* Bring for the next exercise grape-vines. 



EXERCISE 34. 



Grape Tendrils. Examine carefully your specimen of 

 a grape-vine. Remember, branches normally grow from 

 axillary buds, and that, therefore, we expect to find below a 

 young branch a leaf. Note that the tendrils are not in the 

 axils of the leaves, but opposite to them, that the branches 

 of these tendrils are subtend by bracts, which, you know, 

 are rudimentary leaves, and that the upper tendrils 

 are longer and evidently older than the stems from which 

 they seem to spring. We must conclude that, since only 

 stems bear leaves or bracts, grape tendrils are stems. 

 Moreover, not being in the axils of leaves, they must be 

 primary stems. Producing but one 'or two leaves a grape 

 stem develops the succeeding internodes into a branching 

 tendril. The branch at the last normal node becomes the 

 leading stem which at the first or second node becoming 

 a tendril, gives place in turn to its branch, and so on to the 

 end of the vine. In your older and longer specimens there 

 are near the base clusters of flowers or grapes. Their posi- 



* The work on leaves may profitably be continued for several more exercises. 

 Out of school, pupils should observe the habits of leaves. Many leaves change 

 their position or the relative positions of their parts at night. Oxalis leaves and 

 those of most acacias change remarkably. The common mallows leaf when 

 young faces the sun all day. Because of the hanging habit of eucalyptus leaves, 

 aided by their smooth surfaces and acuminate points, they probably send more of 

 a passing fog to the ground than any other tree, besides letting all rain drops slip 

 easily by. 



