96 THE LEAF 



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

 divisions. 



Divided, wlieii tlie incisions extend quite to the midrib, as in the 

 lower part of Fii;-. 119, or to the leafstalk, as in Fig. 12o; -svhich really 

 makes the leaf compound. 



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

 veining, whether pinnatehj reined or palmatety reined. In the former 

 the notches or incisions, or sinuses, coming 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 lohed (in the special sense), the 

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

 parted, the fourth pinnately dirided. 



174. Correspondingly in the lower row, of palmatel}' veined leaves, 

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

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

 same meaning (but now less commonl}' employed), they are said to be 

 digitately lobed, cleft, parted, or dirided. 



175. The uunilier ot the divisions or lobes may come into the 

 plirase. Thus in the lour last named figures the leaves are respectively 

 ptdmately thrce-lobed, three-cleft (or trifiil), three-parted, three-divided. 

 And so for higher numbers, as f re-lohed . fve-cteft, etc., up to manydohed, 

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

 tor pinnately lobed leaves, as pinnately seren-lohed, -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 lohed. parted or dirided leaves, etc. From these 

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

 may describe any one of the almost endle.ssly 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 usuall}' with a stalklet of its own ; 

 and the stalklet is often j'ninted (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 wdiere all intermedi- 

 ate forms may be expected. 



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

 called lohrs. or in deeply cut leaves, etc., srymrnts or dirisions, the sepa- 

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



