SURFACE OF LEAVES- 131 



produced, are greater than in the last named example, 

 as in the Cabbage, a leaf is said to be Bullate or blis- 

 tery. 



A Plaited leaf is folded like a fan, and the American 

 Hellebore is a good example. When the surface of a 

 leaf near its margin is waved obtusely up and down, it 

 is said to be Undulate ; and Curled when the border 

 is so much expanded as to be in regular folds, as in the 

 Curled-leaved Mallows. 



When the middle of a long and narrow leaf is furrow- 

 ed or depressed it is said to be Chanelled, as in Narcis- 

 sus and Hyacinths. And when the midrib is prominent, 

 on the inferior surface of a leaf, as in the Indian Corn, 

 it is said to be Keeled. 



A leaf is Veined when the vessels arise from it midrib, 

 as in the Cherry and Elm. 



It is Nerved^ when arising from the petiole, its vessels 

 are continued from the base to its summit, as in Ladies 

 Slipper and Solomon's seal. When these nerves are 

 three, a leaf is termed three-nerved or three-nerved at 

 the base, when as in the Burdock and Sunflower, the 

 two lateral nerves pass for a considerable distance 

 along the margin of the leaf. When these nerves arise 

 above the base of a leaf it is said to be triply-nerved, as 

 in Ceanothus Americanus. 



When the vessels of a leaf intersect each other so as 

 to form a net- work, a leaf is said to be Reticulate. 

 This is well seen in the Rattle snake Plantain, JVeottia 

 pubescens, whose white veins present a very obvious 

 contrast with the dark green colour of the interven- 

 ing cells. 



The surface of a Lineate leaf is slightly marked lon- 

 gitudinally with depressed parallel lines. 



When no vessels are apparent on the surface of a leaf 

 it is said to be Nerveless or even, as in Marsh Rose- 

 mary. 



