Population variation in Plantago major from southern Ontario

Abstract

The morphological variation and growth and flowering responses in 15 populations of Plantago major collected from different climatic regions and habitat types in southern Ontario were examined. Both within- and between-population differences were assessed using canonical variates analyses. These were carried out on data obtained from field-collected specimens, and from plants grown from seed for a 2-year period in a standard garden trial. Four groupings of the 15 population samples were recognized in the field data. These included the two lawn populations, 8 and 15; population 14, collected from a cultivated field; population 9, originating from a nonmown wasteground site; and the remaining populations collected from a range of trampled roadside – waste ground sites. Analyses of the garden trial data indicated similar groupings. Population 14 remained a distinct group containing individuals characterized by long narrow leaves, a semiprostrate growth form, earlier flowering, greater reproductive effort, reduced rosette production, a larger number of seeds per capsule, and smaller seeds. These individuals would appear to correspond to ssp. pleiosperma. The remaining population samples were characterized by a smaller number of seeds per capsule, larger seeds, a smaller reproductive effort, and later flowering and they would appear to be referable to ssp. major. The two lawn populations, 8 and 15, contained the largest number of prostrate individuals, which were smaller in size and produced less biomass than individuals in the remaining populations. The latter group consisted of large erect plants which produced considerable floral and vegetative growth. There was no evidence for clinal patterns of variation in flowering behaviour and growth features in relation to the climatic gradients in southern Ontario among the 15 populations of P. major.