SECTION 7.] 



ORDINARY LEAVES. 



57 



etc., up to many-lobed, many-cleft or multifid, etc. The same mode of ex- 

 pression may be used for piimately lobcd leaves, as pinnately 1 -lobed, -cleft, 

 -parted, etc. 



145. The divisions, lobes, etc., may themselves be entire (without teeth 

 or notches), or serrate, or otherwise toothed or incised; or lobed, cleft, 

 parted, etc. : in the latter cases making twice pinnatifid, twice palma lely or 

 pinnately lobcd, parted, or divided leaves, etc. From these illustrations 

 one will perceive how the botanist, in two or three words, may describe 

 any one of the almost endlessly diversified shapes of leaves, so as to give a 

 clear and definite idea of it. 



146. Compound Leaves. A compound leaf is one which, has its blade 

 in entirely separate parts, each usually with a stalklet of its own; and the 

 stalklct is often jointed (or articulated} with the main leaf-stalk, just as this 



158 



is jointed with the stem. Wheu. this is the case, there is no doubt that 

 the leaf is compound. But when the pieces have no stalklets, and are not 

 jointed with the main leaf-stalk, it may be considered either as a divided 

 simple leaf, or a compound leaf, according to the circumstances. This is 

 a matter of names where all intermediate forms may be expected. 



147. While the pieces or projecting parts of a simple leaf-blade are 

 called Lobes, or in deeply cut leaves, etc., Segments, or Divisions, the sep- 

 arate pieces or blades of a compound leaf are called LEAFLETS. 



148. Compound leaves are of two principal kinds, namely, the Pinnate 

 and ft&Palmate; answering to the two modes of veining in reticulated 

 leaves, and to the two sorts of lobed or divided leaves (111). 



149. Pinnate leaves are those in which the leaflets are arranged on the 

 sides of a main leaf-stalk; as in Fig. 15G-15S. They answer to the 



FIG. 156-158. Pinnate leaves, the first with an odd leaflet (n,7t?-ptn>i(i-); the 

 second with a tendril in place of uppermost leaflets ; the third abruptly pinnate, 

 or of even pairs. 



