LEAVES, THEIR FORM AND MOVEMENT 



completely or partly around the stem for some distance, and is 

 called the sheath, while the blade is free. In the Indian corn 

 and some other Gramineae 

 there is a membranous 

 growth arising from the 

 junction of the sheath and 

 blade which lies close around 

 the stem. This is the ligule. 

 118. Venation of leaves. 

 -The blade of the leaf is 

 prominently marked by lines, 

 in the form, usually, of eleva- 

 tions, especially on the un- 

 derside, while the lines are 

 also seen distinctly on the 

 upper side of the leaf. These 

 are called veins of the leaf. 

 Some of these veins are quite Fig. 6 4 . 



large and. prominent, while Leaf of corn, showing blade, sheath, and ligule. 



c. 



D. 



A. , Fig. 65. 



A. Leaf of apple, showing persistent stipules at base of petioles, a pinnate, reticulate, 

 veined leaf, edge serrate. B. Leaf of beech, pinnate, reticulate venation, edge serrate. 

 C. Leaf of laurel, edge plain. D. Leaf of holly, edge spiny. 



others are smaller and less conspicuous. Within the veins are the 

 vascular bundles, which are continuous through the petioles with 



