_Peltate_, or _Shield-shaped_ (Fig. 132), is the name applied to a curious modification of the leaf, commonly of a rounded form, where the footstalk is attached to the lower surface, instead of the base, and therefore is naturally likened to a shield borne by the outstretched arm. The common Watershield, the Nelumbium, and the White Water-lily, and also the Mandrake, exhibit this sort of leaf. On comparing the shield-shaped leaf of the common Marsh Pennywort (Fig. 132) with that of another common species (Fig. 130), it is at once seen that a shield-shaped leaf is like a kidney-shaped (Fig. 130, 131) or other rounded leaf, with the margins at the base brought together and united. 137. =As to the Apex=, the following terms express the principal variations:-- _Acuminate_, _Pointed_, or _Taper-pointed_, when the summit is more or less prolonged into a narrowed or tapering point; as in Fig. 133. _Acute_, ending in an acute angle or not prolonged point; Fig. 134. _Obtuse_, with a blunt or rounded apex; as in Fig. 135, etc. _Truncate_, with the end as if cut off square; as in Fig. 136. _Retuse_, with rounded summit slightly indented, forming a very shallow notch, as in Fig. 137. _Emarginate_, or _Notched_, indented at the end more decidedly; as in Fig. 138. _Obcordate_, that is, inversely heart-shaped, where an obovate leaf is more deeply notched at the end (Fig. 139), as in White Clover and Wood-sorrel; so as to resemble a cordate leaf inverted. _Cuspidate_, tipped with a sharp and rigid point; as in Fig. 140. _Mucronate_, abruptly tipped with a small and short point, like a mere projection of the midrib; as in Fig. 141. _Aristate_, _Awn-pointed_, and _Bristle-pointed_, are terms used when this mucronate point is extended into a longer bristle-form or slender appendage. The first six of these terms can be applied to the lower as well as to the upper end of a leaf or other organ. The others belong to the apex only. [Illustration: Fig. 133-141. Forms of the apex of leaves.] 138. =As to degree and nature of Division=, there is first of all the difference between _Simple Leaves_, those in which the blade is of one piece, however much it may be cut up, and _Compound Leaves_, those in which the blade consists of two or more separate pieces, upon a common leaf-stalk or support. Yet between these two kinds every intermediate gradation is to be met with. [Illustration: Fig. 142-147. Kinds of margin of leaves.] 139. =As to Particular Outlines of Simple Leaves= (and the same applies to their separate parts), they are _Entire_, when their general outline is completely filled out, so that the margin is an even line, without teeth or notches. _Serrate_, or _Saw-toothed_, when the margin only is cut into sharp teeth, like those of a saw, and pointing forwards; as in Fig. 142. _Dentate_, or _Toothed_, when such teeth point outwards, instead of forwards; as in Fig. 143.