44 



THE LEAP BUD. 



plant in the internodes of the stem or branches, on the root, or eve, 

 leaves. 



208. CAUSES AND EXAMPLES. Such buds generally result from som 

 abnormal condition of the plant, from pruning or other destruction < 

 branches or stem above, while the roots remain in full vigor; thus dc 

 stroying the equilibrium of vital force between the upper and lowe. 

 axis. The leaf of the walking-fern emits rootlets and buds at its apex* 

 the leaf of Bryophyllum from its margin, each bud here also preceded b; 

 a rootlet. Some plants are thus artificially propagated in conservato- 

 ries from the influence of heat and moisture on a leaf or the fragment 

 of a leaf. 



209. VERNATION OB PR^EFOLIATION are terms denoting the mode o 

 arrangement and folding of the leaf-organs composing the bud. Thi 

 arrangement is definitely varied in different orders of plants, furnishir^ 

 useful distinctions in systematic botany. 



210. THE VERNATION OF THE BUD is EXHIBITED in an interesting mau 

 ner by making with a keen instrument a cross-section of it in its swolle* 

 state, just before expansion ; or it may be well observed by removin. 

 one by one the scales. 



211. THE FORMS OF VERNATION are entirely analogous to those o 

 aestivation, and denoted by similar terms. We shall here notice onl 

 such as are more peculiar to the leaf-buds. 



212. VERNATION is considered in two different aspects, first, th 

 manner in which the leaf itself is folded ; second, the arrangement > 

 the leaves in respect to each other. This depends much upon th 

 phyllotaxy. ( 220.) 



71 72 73 74 75 76 



Vernation, 71, of oak leaf ; 72, of Liriodcndron (tulip tree) ; 73, of fern ; 

 75, sage; 76, iris. 



r4, of carex; 



213. EACH LEAF ALONE CONSIDERED is either flat and open, as in thd 

 mistletoe, or it is folded or rolled, as follows : 



Reclined, when folded crosswise with apex bent over forward towards 

 the base as in the tulip-tree. 



Conduplicate, when folded perpendicularly, with the lateral halves 

 brought together, face to face, as in the oak. 



