8o 



PLANT BIOLOGY 



Obovate, ovate inverted, the wide part towards the apex. 



Leaves of mullein and leaflets of horse-chestnut and 

 V false indigo are obovate. This form is commonest 



in leaflets of digitate leaves : why ? 

 Reniform, kidney-shaped. This form is sometimes seen in 



wild plants, particularly in root-leaves. Leaves of 



wild ginger are nearly reniform. 

 Orbicular, circular in general outline. Very few leaves are 



perfectly circular, but there are many that are 



nearer circular than any other shape (Fig. 107). 



FIG. 107. ORBICULAR 

 LOBED LEAVES. 



FIG. 108. TRUNCATE 

 LEAF OF TULIP TREE. 



The shape of many leaves is described in combinations 

 of these terms : as ovate-lanceolate, lanceolate-oblong. 



The shape of the base and apex of the leaf or leaflet 

 is often characteristic. The base may be rounded (Fig. 

 104), tapering (Fig. 93), cordate or heart-shaped (Fig. 105), 

 truncate or squared as if cut off. The apex may be blunt 

 or obtuse, acute or sharp, acuminate or long-pointed, trun- 

 cate (Fig. 108). Name examples. 



The shape of the margin is also characteristic of each 

 kind of leaf. The margin is entire when it is not in- 

 dented or cut in any way (Figs. 99, 103). When not 



