54 



LEAVES. 



[SECTION 7. 



rally likened to a shield borne by the outstretched arm. The common 

 Watershield, the Nelumbium, 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 only. 



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 which the blade consists of two or more sep- 

 arate pieces, upon a common lraf-stalk or support. Yet between these two 

 kinds every intermediate gradation is to be met with. 



139. As to Particular Outlines of Simple Leaves (and the same 

 applies to their separate parts), they are 



Fig. 133-141. Forms of the apex of leaves. 



