ALDER BUCKTHORN 291 



leaves silky. Petiole long and slender, reddish, channelled, 

 pubescent at the base. Stipules obsolete. No stomata 

 on the upper surface. Autumn leaves yellow. 



Venation pinnate-reticulate, the secondaries running 

 towards, but not reaching the entire margin ; rapidly 

 curving, looping, and breaking into a close meshwork of 

 tertiaries, which often leave the outer side at acute, the 

 inner side at open angles, and form distinct cross-ties. 

 Secondaries leave the midrib at very acute angles, few, 

 2 4 each side, strong, approximated towards the base of 

 the leaf, and tending to converge towards the apex, as in 

 pinnate-arcuate venation. Tertiaries also strong and re- 

 ticulation therefore very prominent below. 



Petiole relatively short ; leaf not promi- 

 nently reticulate. 



n Venation pinnate-arcuate. 



Rhamnus Frangula, L. Alder Buckthorn (Fig. 112). 

 Shrub with dark foliage, and yellow malodorous cortex, 

 bitter, and staining the saliva yellow. Leaf broadly elliptic 

 or ovate to obovate or oblong, obtuse or acuminate, 

 4 7 x 2 5 cm. ; entire or very slightly undulate, glabrous 

 or with faint pubescence on the veins or in their angles 

 beneath. Thin, green and rather matt above, paler and 

 brighter beneath. Venation not prominent. Petiole short 

 (5 10 mm.), stipules minute, subulate, caducous. Autumn 

 leaves reddish and green. 



Venation pinnate-arcuate and looped. The midrib 

 gives off about 8 strong secondaries rather close together 

 on either side in pinnate fashion. These start nearly 

 straight, but curve strongly forwards beneath the margin, 

 and tend to form slight and inconspicuous loops close 

 beneath it, and then break into the network. Secondaries 



192 



