LECT. X.] COMPOUND LEAVES. 519 



footstalk in autumn, in the same manner as the 

 leaf detaches itself from the tree. Every ex- 

 pansion, therefore, in a compound leaf, is an in- 

 dividual leaf; and it assumes different forms on 

 different plants, in the same manner as the simple 

 leaf. All compound leaves may be arranged under 

 the three following divisions : simply compound 

 (composita) ; doubly compound (decomposita) ; 

 more than doubly compound (supradecomposita). 



1. The simply compound leaf consists of a 

 common petiole only, supporting two or more 

 leaflets. 



When the leaflets are sessile, attached to the 

 apex of the petiole, and three in number, the 

 leaf is termed trifoliate or ternate (trifoliolatum, 

 ternatum), 82 ; as in the genus Clover, Trifolium, 



