Bitterbrush is normally a semierect or low -growing shrub, 1^ to 

 6 feet high. When growing on exceptionally favorable sites it oc- 

 casionally attains a height of 9 or 10 feet and assumes the form of a 

 small tree. It is long-lived and exceptionally drought-resistant and 

 thrives under rigorous conditions. 



Desert bitterbrush (P. glandulo' sa) is the only other species of 

 this genus. The range of this species is restricted to desert areas 

 of southern Nevada and southern California. It resembles P. tri- 

 demtata, but is a dark green shrub with hairless, or practically hair- 

 less, evergreen leaves, dotted with impressed glands on the inrolled 

 edges. In contrast, the less persistent leaves of P. tridentata are 

 white-woolly underneath and green and fine-hairy on the upper- 

 surfaces. 



