Vernation 



65 



When the leaf is rolled on itself, one margin being rolled to- 

 wards the midrib, and the other margin rolled over it, as in 

 the Apricot and Banana (v.), the folding is convolute. When 

 the two margins are rolled towards the midrib on the under 

 side of the leaf, as in the Dock and Rosemary (vi.), it is revolute. 

 When the margins are rolled in the opposite way, that is, to- 

 wards the upper surface of the leaf, as in the Violet and Water 

 Lily (vii.), it is involute. 



(The diagrams of vernation are often at first hard to under- 

 stand, unless we remember they represent sections cut across 

 the leaves. A good plan is to cut out a large leaf in paper and 

 to bend it in the forms described, after which an examination 

 should be made of actual specimens.) 



Fig. g8.— Forms of leaf-arrangement in bud. 



2. The disposition of the several leaves in the bud. — In this 

 case the leaves are either flat, or only slightly convex, or they 

 are bent or rolled. 



(a) Leaves flat or only slightly convex. — The vernation is 

 valvate (fig. 98, i.) when the leaves are placed in the same 

 level and simply touch one another by their edges. If they are 

 placed at different levels and overlap one another like tiles of a 

 foof, as in the Lilac (n. and iii.), it is imbricate. When the 



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