74 



MANUAL OF BOTANY 



shape of the lamina we mean the superficial aspect or the figure 

 which is described by its margins. The development of the 

 wings is usually nearly equal on the two sides of the midrib or 

 petiole, so that the lamina of the leaf is in most instances nearly 

 symmetrical and of some regular figure ; in which case the leaf 

 is said to be equal (figs. 137-140). When, as occasionally 

 happens, the wing is more developed on one side than on the 

 other, the leaf is termed unequal or oblique (figs. 129 and 131) ; 

 this is remarkably the case in the species of Begonia (fig. 132). 

 Generally speaking, entire leaves with parallel or pinnate venation 



Fig. 142. 



Fig. 143. 



Fig. 141. 



Fig. 

 144. 



Ul. Spathulate leaf. Fig. 142. Oval 



or elliptical leaf of Pear-tree {Pyrus com- 

 munis)^ with serrate margins. Fig. 143. 



Keuiform leaf of Gronnd Ivy (Nepeta Gte- 



clwma), with crenate margins. Fig. 144. 



Trifoliate leaf with obcordate leaflets. 



are longer than broad ; while those which are palmately veined 

 are more or less rounded, or broader than long. 



"When the lamina of a leaf is nearly of the same breadth at 

 the base as it is near the apex, narrow, and vidth the two margins 

 parallel (figs. 115, a, and 133), the leaf is called linear, as in 

 the Marsh Gentian (Gentiana Pneumonanthe) and most Grasses ; 

 when a linear leaf terminates in a sharp rigid point Uke a needle, 

 as in the common- Juniper (fig. 135), and many of our Firs and 

 Larches, it is acerose or needle-shaped. "When the blade of a 

 leaf is very narrow and tapers from the base to a very fine point, 

 so that it resembles an awl in shape, as in the common Furze 

 (TJlex eu/ropmus), the leaf is subulate or awl-shaped. When the 

 blade of a leaf is broadest at the centre, three or more times as 

 long as broad, and tapers perceptibly from the centre to both 



