FIXATION OF NITROGEN BY BITTERBRUSH (PURSHIA TRIDENTATA (PURSH) DC)

The nodules on bitter-brush have the same coralloid morphology and white color as those of Ceanothus. and a Streptomyces species has been isolated from bitter-brush nodules which has characteristics similar to the Streptomyces species isolated from Ceanothus velutinus nodules. That this organism is the endophyte still remains to be confirmed by pure culture inoculation and nodulation. Bitterbrush is widely distributed throughout the ponderosa pine (Pinus ponderosa Laws.) forests and open range lands in the western United States. Although much remains to be learned about the nodulation and nitrogen fixation process in bitterbrush, the results imply that it is making a significant contribution to the N economies of the ecosystems in which it occurs.