Assessment of the Status of Blowout Beardtongue (Penstemon haydenii S. Watson, Plantaginaceae) using Molecular and Morphometric Approaches
We studied molecular and morphological variation in Nebraska and Wyoming populations of the endangered plant Penstemon haydenii to assess the monophyly of the species and determine its relationship to other closely related species in the genus, and to characterize morphological differences among populations.
RADseq phylogenomic analyses that included 77 species from 10 sections of Penstemon provided the first robust phylogeny for parts of the genus. Our analyses confirmed that all species traditionally assigned to section Coerulei, which includes P. haydenii, are members of that section, and that some other species historically assigned to other sections of Penstemon also belong in section Coerulei.
Wyoming populations of P. haydenii were found to be more closely related to each other than they are to Nebraska populations, and the species was found to be monophyletic and sister to two other psammophytic species of the south-central and southwestern U.S.
Morphometric studies using univariate statistical analyses of data from herbarium specimens revealed statistically significant differences between Nebraska and Wyoming populations, and principal component analyses showed that Nebraska and Wyoming plants form fairly discrete clusters. Both molecular and morphological data provide support for treating Nebraska and Wyoming populations as distinct varieties.