FORMS OF FOLIAGE-LEAVES. Ill 



the non-development of internodes. The clusters when 

 carefully examined, show in some cases an alternate, and 

 in others a whorled, arrangement. 



165. As branches are produced in the axils of leaves, it 

 is clear that the arrangement of branches will be the same 

 as that of the leaves. It rarely happens, however, that 

 all the buds develope into branches. Many of them fail, 

 so that generally branches appear to have no very definite 

 arrangement. 



166. Vernation or Prsefoliation. These terms have 



reference to the mode in which the new leaves are folded 

 in the bud. Very commonly the leaf is simply doubled 

 lengthwise, the upper side of the leaf within ; then its 

 vernation is said to be conduplicate. In the Maple and 

 Mallow the folding is fan-like, and is described as plaited. 

 In the Cherry the leaf is coiled in a single coil beginning 

 with one edge : this is convolute vernation ; but if the 

 coiling is from both edges to the mid- rib, it is said to be 

 involute ; if both edges are rolled backward, it is revolute. 

 The vernation is circinate when the leaf is coiled from the 

 tip, as in Ferns. 



/ 16/ f. Forms Of Foliage-Leaves. Leaves present 

 an almost endless variety in their forms, and accuracy 

 in describing any given leaf depends a good deal upon 

 the ingenuity of the student in selecting and combining 

 terms.' The chief terms in use will be given here. 



Compare a leaf of the Round-leaved Mallow with one 

 of Red Clover (Figs. 141, 142). Each of them is 

 furnished with a long petiole and a pair of stipules. In 

 the blade, however, there is a difference. The blade of 

 the former consists of a single piece / that of the latter 



