Anatomy and Physiology. 93 



nor the pine with the skunk cabbage. The difference, however, is 

 probably made up in the immense number ; for the exceptions 

 to the general rule, the large leaved trees, bear but very few in 

 comparison with others. 



Vernation or Prefoliation is the name given to the manner 

 in which the future leaves are folded in the bud ; the study of 

 this will richly repay all the trouble bestowed on it, even if no- 

 thing more was gained from it than the opportunity of observing 

 how very closely nature regulates even the minutest operation. 

 In respect to the manner of their folding they are either (see 

 plate), 



1st. Convolute — rolled together : when the margin of one 

 side surrounds the other margin on the same leaf in the manner 

 of a cowl or hood, as in the pepper, lettuce, cranberry, goats- 

 beard, &c., and many grasses. 



2d. Involute — rolled in : when their lateral margins are rolled 

 spirally inwards on both sides, as in the honeysuckle, apple, pear, 

 nettle, elder, buckthorn, water lily, liverwort, buttonwood, &c. 



3d. Revolute — rolled back: when their lateral margins are 

 rolled spirally backward on both sides, as in rosemary, foxglove, 

 primrose, thistle, water pepper, fire-weed, &c. 



4th. Conduplicate — doubled together: when the sides of the 

 leaf are parallel and approach each other, as in the oak, hazelnut, 

 trumpet flower, raspberry, &c. 



5th. Equitant — riding : when the sides of the leaves lie paral- 

 lel, and approach in such manner as the outer embrace the inner, 

 as in the yellow day lily, iris, calamus, sedge, pasture grass, &c. 



6th. Imbricate— when they are parallel with a straight sur- 

 face, and lie one over the other, as in the bell flower, &c. 



7th. Convolute. 8th. Involute opposite. 9th. Obvolute — 

 rolled against each other : when their respective margins alter- 

 nately embrace the straight margin of the opposite leaf, as in the 

 pink, &c. 



10th. Plicate — plaited: when their complication is in plaits 

 lengthwise, as in the passion flower, Guelder rose, hollyhock, &c. 



11th. Involute alternate. 12th. Revolute opposite. 13th. 

 Equitant ancipital. 14th. Equitant triquetrous. 



"When the leaves first shoot they are without any external 

 covering, but the cold of early spring in our climate, chills and 

 hardens them, so that instead of expanding they become chilled 



