VILLICAULES. 99 



setae seated upon minute tubercles which render the old stems 

 rough like a file. 



All the Villicaules are liable to have their stems denuded 

 (calvati) when full grown, and then they are sometimes diffi- 

 cult to distinguish from the Rhamnifolii: but if the younger 

 states of the stem are examined it is believed that the 

 characteristic covering will be always found present in more 

 or less abundance. The stems of the Rlmmnifolii seem never 

 to have setae, nor to be felted, even in their youngest state. 



a Discolores. — Aculei caulis sequales, validi; pube- 

 scentia arete adpressa. Folia subtus cano-tomentosa. 



