FOLIA DIGITALIS. DIGITALIS. 



183 



shape, bluntly pointed, the base is decurrent, extending 

 down the sides of the petiole. They measure 20 to 40 

 cm. in length, 6 to 10 cm. in breadth, with strongly 

 crenulate or crenulate-dentate, sometimes slightly un- 

 dulate, margins. The upper leaves become smaller and 

 are borne on gradually shorter petioles as they ascend. 

 They are more oblong in shape with less crenulate 

 margins. The upper surface is deep-green, paler in 

 younger leaves, smooth or very slightly pubescent. The 

 lower surface is much paler, grayish, and very hairy, and 



Fig. 46. — Cross-sectiom op Digitalis Leaf Showing Midrib of 

 Vascular Bundle and Hairs on the Epidermis. 



is marked by a network of very prominent whitish veins. 

 The secondary veins leave the midrib, which is quite 

 broad at the base, thence tapering upward, at an angle of 

 about 45 degrees, and, following a somewhat undulating 

 course, diverge to the margins, where they recurve. 

 From them branch numerous tertiary veins, which form 

 the coarse network so characteristic of this leaf. 



