Does Dryas integrifolia fix nitrogen?

Symbiotic nitrogen fixation is found in plant taxa that also include non-nitrogen-fixing members. Strong evidence for the occurrence of nitrogen fixation comes from physiological measurements and the identification of the nitrogen fixing symbiont. This evidence has been provided for Dryas drummondii Richardson ex Hook. in the Rosaceae. However, while there have been numerous references to the nitrogen fixing ability of Dryas integrifolia Vahl., they can all be traced to a single report that did not provide strong evidence for nitrogen fixation. My attempts to establish nitrogen fixing nodules on vegetatively propagated plants from the field, or seedlings of D. integrifolia, using three different sources of Frankia, all failed. Since other host plants (Alnus viridis (Chaix) DC. subsp. crispa (Aiton) Turrill and Purshia tridentata (Pursh.) DC.) did produce nitrogen-fixing nodules under the same growth conditions, the ability of D. integrifolia to fix nitrogen should be considered suspect.