VERNATION OK PR^EFOLIATION. 



95 



On making a transverse section of the bud (fig. 204), the over-lying 

 scales, e e e e, are distinctly seen surrounding the leaves, f, which are 

 plaited or folded round the axis or 

 growing point. In plants of warm 

 climates, the buds are often formed by 

 the ordinary leaves without any pro- 

 tecting appendages; such leaf-buds are 

 called naked. 



184. Vernation. The arrangement of 

 the leaves in the bud has been deno- 

 minated vernation (ver, spring), orprce- 

 foUation (prce, before, and folium, leaf), 

 or gemmation (gemma, a bud). This 

 differs in different plants, but in each 

 species it follows a regular law. The e 



leaves in the bud are either placed 



simply in apposition, as in the Misletoe, or they are folded or rolled 

 up longitudinally or laterally, giving rise to different kinds of verna- 

 tion, as delineated in fig. 205 a , where the dot represents the axis, 



and the folded or curved lines, the leaves Avith the thickened part indi- 

 cating the midrib ; figs, a and g, being vertical sections ; h n, horizontal. 

 185. The leaf taken individually, is either folded longitudinally from 

 apex to base (fig. 205 a), as in the Tulip-tree, and called reclinate; 

 or rolled up in a circular manner from apex to base, as in Ferns 



Fig. 204. Transverse section of the same leaf-trad e e e e, The scales arranged in an imbri- 

 cated manner, like the tiles on a house. /, The leaves folded in a plaited manner, exhibiting 

 plicate vernation. 



Fig. 205. Figures to show the different kinds of vernation, a g, The folding of individual 

 leaves; a and g being vertical sections, b c d e and/, being horizontal a, Reclinate. 6, Con- 

 duplicate, c, Plicate, d, Convolute. , Involute. /, Revolute. g, Circinate. h n, Folding of 

 leaves when united together in the leaf-bud. The sections are horizontal or transverse, and 

 show the relative position of the leaves, and the mode in which each of them is folded. A, Val- 

 vate. i, Twisted or spiral k I, Induplicate. m, Equitant. n, Obvolute or half-equitant In all 

 the figures, the thickened portion indicates the midrib of the leaf, and the dot marks the position 

 of the axis. 



