32 FIRST LESSONS WITH PLANTS 



joint at any place on the petiolules at which point 

 the three parts may break off in the fall; and is 

 the Virginia creeper like the bean in this respect? 

 37. The leaf of the Canada thistle (Fig. 27),- 

 and of most other thistles, is variously cut or 

 jagged, but is nowhere completely separated, and is 

 not, therefore, a compound leaf. We have seen, 

 then, that there are various gradations between the 

 simple leaf (that is, one in which the blade is one 



FIG. 27. 

 Canada thistle. 



more or less continuous piece, as in Figs. 16, 17, 

 18, 21, 22), and the compound leaf. In the true 

 compound leaf the parts are generally articulated 

 (or separated by joints), and are, therefore, usu- 

 ally provided with petiolules, although these are 

 sometimes wanting. The different parts may fall 

 independently of the entire leaf, or they may 

 not. 



38. Inasmuch as there seems to be a well 



