Interspecific Hybridization within Penstemon and Their Potential Uses in Urban Landscapes

Penstemon,with over 270 different species, is among the largest native genera in NorthAmerica. Commercially acceptable cultivars of both selections within a specific species and Penstemoninterspecific crosses are available in both the North American and European markets;however, these cultivars are almost universally lacking in drought and extreme temperature tolerance. These characteristics, as well as colorful abundant flowers and foliage, are found in the endemic Penstemonof the Intermountain West, which is the center of diversity for this genus. For example, Utah has over 70 native species of this genus with different taxa ranging from mat forming habit to others that grow to at least three feet tall and flower colors ranging

across reds, blues, whites, purples, and florescent pinks. The vast majority of these taxon demonstrate natural tolerance to drought and temperature extremes found in their native desert habitats. Our research focuses on tapping into these desirable characteristics by preforming wide crosses within Penstemonto develop commercially viable, hardy cultivars for use in urban desert landscape environments. As we have worked with Penstemon,we have successfully produced seed from approximately 30 wide crosses involving 20 unique species during the 2015 growing season. Throughout the winter of 2015-2016, we have been attempting germination of the seed although, as could be expected in interspecific hybridization, only a few of these seed are producing viable plants. We currently have three plants from crosses made in 2015 and two plants from crosses in 2014. We have observed that our 2014 wide cross hybrids predominantly exhibit the female plant’s phenotype. This female dominant phenotype in the F1 has been previously reported; however, the F2, sib matings, and backcross generations in these reports have demonstrated segregation of both of the original parent’s characteristics. We are currently unsure why this is. Improving our understanding as to why this phenomenon is taking place in Penstemonis one of the objectives of our research and will help us progress in our long-term goal of developing a commercially acceptable, drought tolerant, disease resistant, and summer long flowering habit for urban landscapes. Thus, our future research will focus on making additional wide crosses as well as developing segregating populations of sib-mating, F2’s, and backcrosses.