2018 ASHS Annual Conference

First found in 1894 by Marcus E. Jones, Penstemon x jonesii Pennell was later described as a species in 1920 by Francis W. Pennell. In 1967, Frank S. Crosswhite hypothesized that it is a natural hybrid of P. laevis and P. eatonii. It is now widely accepted as the putative natural hybrid of those two species. It has been identified in relatively concentrated areas in Southwestern Utah. This taxon has long been recognized as a candidate for horticultural selections due to its beautiful “Tyrian rose”, “amaranth purple”, or red-purple to maroon colored blooms (Neese). Understanding the phylogenetic relationships of this taxon is valuable to assist in the development of cultivars derived from P. x jonesii for urban landscapes. In conflict with the claim of the natural hybridization of the two aforementioned Penstemon species, P. x jonesii exhibits phenotypic incongruencies with controlled experimental crosses of P. eatonii x P. laevis, which have bloomed in our greenhouse. Using ten Penstemon microsatellite markers we have been examining the allelic variations between P. x jonesii, P. eatonii, and P. laevis. Our preliminary results suggest that P. x jonesii is not a first generation (F1) hybrid of P. eatonii and P. laevis. These early SSR data suggest that P. x jonesii is more closely related to P. eatonii, than P. laevis. We now have reciprocal hybrid plants of the two parental species (P. eatonii and P. laevis); as well as hybrid plants growing where P. x jonesii was the male parent in crosses with P. eatonii. All of our preliminary data support our working hypothesis that P. x jonesii is more closely related to P. eatonii than P. laevis.