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 



