DOES ARCTOSTAPHYLOS UVA-URSI (BEARBERRY) HAVE NITROGEN-FIXING ROOT NODULES?

An earlier report of the presence of Alnus-type nitrogen-fixation root nodules on Arctostaphylos uva-ursi (bearberry) has been re-examined. Nodular structures, externally resembling those of alder, were observed at four locations in eastern North America and in northern Scotland. No endophytes could be found in these structures and repeated assays by the acetylene reduction technique failed to demonstrate their ability to fix dinitrogen in North American material. The structures, in microscopic section, possessed typical bud morphology, could be sprouted in a moist chamber and produced shoots under stressed conditions in the field. The suspected 'nodules' are probably latent buds, serving to re-establish bearberry plants following damage.