96 THE LEAF 



the terms two-parted, three-parted, etc., express the number of such 

 divisions. 



Divided, when the incisions extend quite to the midrib, as in the 

 lower part of Fig. 119, or to the leafstalk, as in Fig. 123; which really 

 makes the leaf compound. 



172. The mode of lobing or division corresponds to that of the 

 veiuiug, whether pinnately veined or palmately veined. In the former 

 the notches or incisions, or sinuses, corning between the principal veins 

 or ribs are directed toward the midrib : in the latter they are directed 

 toward the apex of the petiole ; as the figures show. 



173. So degree and mode of division may be tersely expressed in 

 brief phrases. Thus, in the four upper figures of pinnately veined 

 leaves, the first is said to be pinnately lobed (in the special sense), the 

 second pinnately cleft (or pinnatifid in Latin form), the third pinnately 

 parted, the fourth pinnately divided. 



174. Correspondingly in the lower row, of palmately veined leaves, 

 the first is palmately lobed, the second palmately cleft, the third palmately 

 parted, the fourth palmately divided. Or, in other language of the 

 same meaning (but now less commonly employed), they are said to be 

 digitately lobed, cleft, parted, or divided. 



175. The number of the divisions or lobes may come into the 

 phrase. Thus in the four last named figures the leaves are respectively 

 palmately three-lobed, three-cleft (or trifid), three-parted, three-divided. 

 And so for higher numbers, as Jive-lobed, Jive-cleft, etc., up to many-lobed, 

 many-cleft, or multifid, etc. The same mode of expression may be used 

 for pinnately lobed leaves, as pinnately seven-lobed, -cleft, -parted, etc. 



176. 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 

 palmately or pinnately lobed, 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. 



177. 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 stalklet is often jointed (or articulated) with the main leaf- 

 stalk, just as this is jointed with the stem. When 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 leafstalk, it may be con- 

 sidered either as a divided simple leaf, or a compound leaf according 

 to the circumstances. This is a matter of names where all intermedi- 

 ate forms may be expected. 



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

 called lobes, or in deeply cut leaves, etc., segments or divisions, the sepa- 

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



