96 



MORPHOLOGY OF LEAVES. 



term oblanceolate is superfluous. The following terms desig- 

 nate leaves with a notched instead of narrowed base. 



Cordate, or Heart-shaped, when a leaf of an ovate form, or 

 something like it, has the outline of its rounded base turned in 

 (forming a notch or sinus) where the stalk is attached, as in 

 Fig. 172, 151. Also Fig. 149, Pontederia, a leaf of the parallel- 

 veined class. 



Reniform, or Kidney-shaped, like the last, only rounder and 

 i broader than long. (Fig. 158.) 



Auricnlate, or Eared, having a pair of small and blunt pro- 

 jections, or ears, at the base, as in Magnolia Fraseri, Fig. 178. 

 Sagittate, or Arrow-shaped, where such ears are acute and turned 



downwards, while the 

 main body of the blade 

 tapers upwards to a 

 point, as in the com- 

 mon species of Sagit- 

 taria or Arrow-head, 

 and in the Arrow- 

 leaved Polygonum. 

 (Fig. 165, 177.) 



Hastate, or Halberd- 

 shaped, when such 

 lobes at the base point outwards, giving the leaf the shape of the 

 halberd of the olden time, as in Polygonum arifolium (Fig. 170) 

 and Sorrel, Fig. 163. 



182. Peltate or Shield-shaped leaves are those in which a blade 

 of rounded or sometimes of other shape is attached to the petiole 

 by some part of the lower surface, instead of the basal margin : 

 those of Water-shield or Brasenia, of Nelumbium, and of Hydro- 

 cotyle umbellata are marked examples. The anomaly is mor- 

 phologically explained by a comparison with deepty cordate or 

 reniform leaves having a narrow sinus, such as those of N}'m- 

 phaea or Water Lily, and by supposing a union of the approxi- 

 mated edges of the sinus. Fig. 159 and 160, from two species 

 of Hydrocotyle, one with open and the other with closed sinus 

 obliterated by the union, illustrate this. 



183. As to Extremity, whether base or apex, there are several 

 descriptive terms, expressive of the principal modifications ; 

 such as 



Acuminate, tapering, either gradually or abruptly, into a 

 narrow more or less prolonged termination. (Fig. 180.) 



FIG. 177-179. Sagittate, auriculate, and hastate leaves. 



