THE LEAF-BUD. 



73 



2, the manner in which each separate leaf is folded. The general 

 arrangement is called imbricate or valvate, according as the margins 

 of the leaves overlap one another or simply meet without over- 

 lapping ; but more minute distinctions are observed, and these 

 depend to a great extent on the phyllotaxis of the species. Thus 

 with the 5, -f , or other spiral plan, we have usually triquetrous 

 (fig. 126) or quincuncial (fig. 128) imbricate buds proper ; with 

 alternate ^ or distichous leaves the vernation may be equitant (fig. 

 125), where each leaf, sharply folded (condn plicate), completely 



Fig. ]26. Fig. 128. 



Fig. 125. 



Sections through Buds, showing their reciprocal vernation. 

 Fig. 125. Imbricated, and equitant (of a Grass). 

 Fig. 126. Imbricated, triquetrous (of a Carex). 

 Fig. 127. Induplicate, decussate (of the Apple). 

 Fig. 128. Imbricated, quincuncial (of a Poplar). 



embraces its successor (as in the Flag), or Jialf-eqidtant or obvolute, 

 where the leaves are similarly folded, but each leaf embraces only 

 one (lateral) half of the blade of its successor. Valvate buds occur 

 mostly where the leaves are opposite ; a modification of this form 

 exists where the margins of the leaves are rolled inwards (fig. 127), 

 and is called induplicate vernation. 



The individual leaves Y\*. 129. Fig. 130. Fig. 131. 



in a bud are either flat^ 

 folded, or rolled. For the 

 first, of course, no special 

 term is requisite. Of the 

 folded leaves we have : 

 reclinate, or inflexed,where 



the leaf is folded horizon- 

 , -n ., ., . . . 



tally, SO that the point IS 



brought down to the base 

 / r 7 7 x 7 7 . 



(Ltrioclendron) ; condupli- 



cate (fig. 125), where the leaf is folded perpendicularly at the 



Sections through leaves showing their 



individual vernation. 

 Fig . 129 . vernation of a plicate leaf. 

 Fig- 13 - Vernation of a convolute leaf. 

 Fig. 131. Vernation of revolute leaves. 



