58 



THE FLOWERING PLANT. 



{cordate), arrow-shaped {sagittate), kidney-shaped (reniform) leaves, 

 &c, exemplify this (figs. 20. 16, 2 1). The lobes of a sessile lamina 

 of this kind may clasp the stem more or less closely. The leaf is 

 then amjplexicaul. Or they may from the first be united together 

 on the opposite side of the stem, which then appears to pierce the 

 perfoliate leaf. A similar origin {i.e., union of lobes) accounts 

 for peltate leaves (fig. 17), and two opposite leaves may be con- 

 tinuous or connate. When the lamina passes into a wing on the 

 stem (cf p. 52), the leaf is decurrent. When the blade is broader 

 at the apex, the outline is often similar to that of lanceolate, 

 ovate, cordate, &c., leaves, but reversed. This is expressed by 



Fig. 17.— Peltate Leaf, seen Fig. 18.— Lanceolate, Awl-shaped, 



from below. 



and Whirled Leaves. 



Fig. 19. -Ovate 

 Leaf. 



Fig. 20.— Cordate 

 Leaf. 



Fig. 21.— Kidney-shaped, Elliptical, and Abrupt 

 Leaves. 



prefixing ob, as ol 'lanceolate, obovate. Special regions of the 

 lamina, as extremity and margin, are also very varied in character, 

 and numerous terms are employed in describing. Either ex- 

 tremity, i.e., base or apex, may be more or less pointed, rounded, 

 or notched, and the latter may also be provided with a sharp 

 projection. The margin may be entire, that is, devoid of marked 

 projections and indentations, or it may possess them. In the 

 latter case, the edge may be either undulating or provided with 

 small teeth of various shape. 1 From leaves of this sort we can 

 pass, by intermediate gradations, to lobed or segmented leaves, 



1 Leaves are serrate (fig. 13), with sharp teeth pointing to apex; crenate 

 (fig. 17), with rounded teeth ; dentate, with sharp irregular ones. 



