COMPOUND LEAVES. 



18 



The preceding are called "simple" leaves, because consisting of a 

 single blade or lamina. There is another large class termed " com- 

 pound" leaves, in which numerous small blades or "leaflets," each 

 with a short stalk of its own, are combined into a symmetrical whole. 

 Of these there are two principal forms, and several minor varieties, 

 the important characteristic in every instance being the attachment 

 of the component leaflets to the main stalk by means of a swollen and 



Fig. 15. 



Fig. 17. 



Fig. 16. 



hinge-like joint, which enables them, in many cases, to move upwards 

 and downwards, as in the sensitive-plant and the wood-sorrel. Com- 

 pound leaves are scarcely ever sessile, but on the contrary, usually 

 provided with long petioles. The lotus is the only example of the 

 former among our wild-flowers. 



The following are the chief varieties and their names : — 



" Pinnate " or " feather-like," when several pairs of leaflets proceed 

 laterally from a main stalk. There may be only two or three 

 pairs, or thrice or four times as many, and with or without an 

 odd one at the end. (Figs. 18 and 21.) 



" Doubly-pinnate," when, instead of single leaflets, there are as it 

 were smaller pinnate leaves. 



"Binate," when there are only two leaflets. (Fig. 20.) 



" Trifoliolate," when there are three leaflets. (Fig. 19.) 



