Biosystematics of the genus Populus L. I. Distribution and morphology of native Manitoba species and variants

Abstract

Twenty-four morphological characters of native Manitoba Populus were studied in an attempt to delineate species and variants and provide keys for correct identification. The results support the hypothesis that the variants have originated from intersectional hybridization of P. balsamifera L. (section Tacamahaca Spach.) and P. deltoides Marsh. var. occidentalis Rydb. (section Aegeiros Duby). Populus × jackii Sarg. encompasses the collective group of individuals resulting from this hybrid cross. The hybrid individuals are widely distributed and occur commonly where the two parental species are growing together.