538 THE FLOWERING PLANT. 
(cordate), arrow-shaped (sagittate), kidney-shaped (rentform) leaves, 
&e., exemplify this (figs. 20, 16,21). The lobes of a sessile lamina 
of this kind may clasp the stem more or less closely. The leaf is 
then amplexicaul. 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 (7.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 Fia@. 18.—Lanceolate, Awl-shaped, FIG. 19.--Ovate 
from below. and Whorled Leaves. Leaf. 
FIG. 20.—Cordate Fig. 21.—Kidney-shaped, Elliptical, and Abrupt 
Leaf. Leaves. 
prefixing ob, as oblanceolate, obovate. Special regions of the 
lamina, as extremity and margin, are also very varied in character, 
and numerous terms are employed in describing. Hither ex- 
tremity, t.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.! 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; erenate 
(fig. 17), with rounded teeth ; dentate, with sharp irregular ones, 
