THEIR STRUCTUEE AND FORMS. 



99 



Latin form Bisected, Trisected, &c.), when there are two or three 

 or more complete divisions of the blade. 



189. As to Arrangement of parts, this may be simply and best 

 expressed by taking into account the nature of the venation or 

 the distribution of the ribs, &c., which controls or is co-ordinated 

 with the disposition of the lobes. Pinnately veined leaves, 

 when lobed, must needs have the incisions directed to the mid- 

 rib ; palmately- veined or radiated, to the apex of the petiole. 

 The lobes or divisions of the first will be pinnately , of the second 



palmately disposed. Accordingly, the three leaves of as many 

 species of Oak, Fig. 195, 196, and 197, represent respectively a 

 pinnately lobed, pinnately cleft, and pinnately parted leaf, while the 

 accompanying leaf of Celandine, Fig. 198, is pinnately divided. 

 The first three, however, when the degree of incision is not par- 

 ticularly in question, usually pass under the common term of 

 pinnatifid, Fig. 195 moderately, Fig. 197 deeply. The number 

 x>f lobes, when definitely marked, may come into the descriptive 

 phrase, as pinnately 7-lobed, pinnately 1 -cleft, parted, or divided, 

 as the case may be. 



190. Similarly, Figures 199 to 202 represent, respectively, a 

 palmately three-lobed, three-cleft, three-parted, and three-divided, or, 

 in Latin form, trilobate, trifid, tripartite, and trisect or trisected 

 leaf. Fig. 166 is a palmately ^-parted leaf; Fig. 164, palmately 



FIG. 195-198. Pinnatcly lobed, cleft, parted, and divided leaves. 

 FIG. 199-202. Palmately 3-lobed, cleft, parted, and divided leaves. 



