controlled reciprocal pollinations between "p. occidentalis" and "p. orientalis" resulted in good yields of germinable seed and true hybrid seedlings. crosses of both species, as females, with "p. racemosa" and "p. wrightii" produced extremely low yields of germinable seed, but true hybrids were obtained from all interspecific combinations. apomixis (asexual reproduction from non-fertilized seeds) appeared common in "p. orientalis".