3° 



PART I. ORGANOGRAPHY. 



the more common forms and the terms used in describing them. 

 For the most part leaves, whether simple or compound, incline 

 to bi-laterally symmetrical forms, that is, the two sides of the 

 leaf are counterparts of each other in size and shape, but it some- 

 times occurs, as in the Begonias, Fig. 

 64, that one side is much better 

 developed than the other. Such 

 leaves are termed inequilateral. It 

 not infrequently happens that the 

 bases of simple leaves and the leaf- 

 lets of compound ones show a slight 

 inequality. 



Simple Leaves. A simple leaf 

 F,G - 64 - is one which has a single blade, 



which may either be sessile or petiolate, but if the latter, petiole 

 and blade are united directly and not by means of a joint. We 

 may conveniently describe simple leaves and the separate blades 

 of compound leaves, as to general outline, apex, base, marginal 

 indentations, surface and texture. 



f 



W 



Fig. 65. Fig. 66. Fig. 67. 



Fig. 68. Fig. 69. Fig. 70. Fig. 71. Fig. 72. 



(a) General Outline. By this we mean the outline form of 

 the leaf, disregarding marginal indentations and slight irregular- 

 ities. The principal forms are the linear, a narrow, elongated 

 form, with parallel margins, as represented in Fig. 65 ; the 

 oblong, which is broader, but considerably longer than wide, with 

 sides nearly parallel and ends rounded, Fig. 66 ; the elliptical, 

 somewhat longer than wide, with rounded ends and sides, Fig. 

 67 ; the oval, or broadly elliptical, Fig. 68 ; the lanceolate, or 

 lance-shaped, Fig. 69 ; the oblanceolate, or inversely-lance- 

 shaped, Fig. 70 ; the ovate, which is shaped like the longitudinal 



