HarveyC, I sent you a PM.
Here is a good thread on the point that HarveyC raises.
FYI. On the University of California Wolfskill Experimental Orchards website, they mention both USDA and NCGR in a discussion of the land and orchards.
In 1980 the Department of Pomology and the University of California, Davis, signed a long-term lease agreement with United States Department of Agriculture (USDA) Agriculutural Research Service (ARS) to establish the orchards of the National Clonal Germplasm Repository at Wolfskill.
This repository (a living library of now-obscure fruit) includes stonefruit (peach, plum, nectarine, apricot, almond, prune), grape, walnut, pistachio, persimmon, walnut, olive, pomegranate, fig, and kiwifruit germplasm.