A study of Populus species and interspecific hybrids native to southern Manitoba

Abstract

Four Populus species and numerous variants native to southern Manitoba were collected in 1967 and 1968. The range of variation and mean values for twenty-four morphological characters were obtained for P. tremuloides, P. balsamifera, P. deltoides var. occidentalis and three variant collections. The mean values for most characters in the variants collection were most nearly intermediate between the means of P. balsamifera and P. deltoides var. occidentalis. Phenological dates in 1968 revealed that a fairly effective seasonal isolation separates P. tremuloides from both P. balsamifera and P. deltoides var. occidentalis. The variants flowered at the same time as P. balsamifera and P. deltoides var. occidentalis. Most variants were found to be fertile and seed produced germinated nearly as well as in P. balsamifera and P. deltoides var. occidentalis. The fertility of the variants indicated that complex intragradation of the hybridizing species is possible. This is occurring in the Delta area where most introgression appears in the chromatograms of methanolic bark extracts from the four species. It was possible to separate all four species on the basis of gas chromatography. The chromatograms of the variants were closely similar and had one major component that would appear to confirm P. balsamifera as their parent.