Revisiting the taxonomy of Populus lasiocarpa × P. wilsonii hybrids

Abstract

Although hybrids between Populus lasiocarpa and P. wilsonii have been known for many years, they have not been given a valid nothospecies name. Resolving the classification issue of these bigleaf poplars is now even more necessary because they are known not only from cultivation, but recent evidence confirms their spontaneous occurrence in Hubei Province, China (Zhang, unpublished information). The two species were first artificially crossed in 1956 in Poland and again independently in 1974 in Sweden. Initially, this taxon was described as P. ×wilsocarpa (Bartkowiak & Bugała, 1978). However, this name was invalid due to the lack of Latin diagnosis (which was required at that time) and lack of type designation. In 1996, Böcker and Koltzenburg proposed the name P. ×kornicensis for this hybrid, but it too was invalid for similar reasons and lack of description. In our work, we revisited these poplars and validated the name proposed by Böcker and Koltzenburg by providing a description and type designation. Considering the overall appearance of these hybrid poplars (silhouette, branching pattern), they bear a closer resemblance to P. wilsonii. Other analyzed morphological features are mostly intermediate compared to the parent species, but overall, they lean slightly more towards P. lasiocarpa. We highlight the main diagnostic characteristics that distinguish these species.