. The elements of botany for beginners and for schools. Plants. 54 LEAVES. [section 7. rally likened to a shield borne by the outstretched arm. The common Watershield, the Nelumbiuin, and the White Water-lily, and also the Man- drake, 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 aud united. 137. As to the Apex, the following terms expres
. The elements of botany for beginners and for schools. Plants. 54 LEAVES. [section 7. rally likened to a shield borne by the outstretched arm. The common Watershield, the Nelumbiuin, and the White Water-lily, and also the Man- drake, 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 aud united. 137. As to the Apex, the following terms express the principal varia- tions : — 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 appen- dage. 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 140 141 138. As to degree and nature of Division, there is first of all the dif- ference between Simple Leaves, those in which the blade is of one piece, however much it may be cut up, and Compound Leaves, those in
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Keywords: ., bookcentury1800, bookdecade1880, booksubjectplants, bookyear1887
