50 



LEAVES. 



of the midrib are nearly or quite as ^''s- ^^ 



large as the midrib itself, they are 

 called ribbed leaves. When the pe- 

 tiole expands from its summit at 

 nearly right angles, and in all direc- 

 tions, it constitutes the radiated form 

 of leaves. The end of the leaf, 

 toward the stem, is called the base, 

 the opposite end the apex or summit. 



80. The figure or outline of leaves 

 is produced by the development of 

 the veins and the cellular tissue. 



The more common forms are the 

 following :— When a leaf is bounded 

 by a regular curve, and is three or 

 more times as long as it is broad, it 

 is called oval or oblong. (Fig. 43.) 



It is said to be ovate when it has 

 the outline of the longitudinal section 

 of an.egg. (Fig. 44.) 



Lanceolate^ when it is three or more 

 times as long as it is broad, and 

 rounded at the base, and tapering at the apex. (Fig. 45.) 



Keticulated veined leaf. 



Fig. 45. 



Fig. 44. 



Fig. 43. 



Obiong leaf. 



Ovate leaf. 



Lanceolate leaf. 



Ensiform, when it is sword-shaped, being very long com- 

 pared with its width, as in the Iris and Flag. 

 Beniform, when it is kidney-shaped. (Fig. 46.) 

 Spathulate, broad at the apex, and gradually tapering into 

 the petiole. (Fig. 4Y.) 



What are ribbed leaves ? What are radiated leaves ? What is the ^aso 

 of a leaf ? The apex ?— 89. How is the form of a leaf prodiiced ? \N hat i> 

 anovalleaf? Ovate? Lanceolate? Ensiform? Kenitorm? Spathulatc^ 



