Sexual composition of populations of Fragaria virginiana (Rosaceae) collected from Minnesota and western Wisconsin

Abstract

Populations of Fragaria virginiana Miller collected from 39 sites in Minnesota and western Wisconsin were gynodioecious, in that 35% of the plants were pistillate, 65% were hermaphroditic with perfect flowers, and none were staminate, when scored for gender expression in greenhouse or field plantings. Instability of gender expression across environments was apparent in 15% of the collections and these genotypes that appeared to change gender were termed weak hermaphrodites. Variation in gender composition of collections was not related in any consistent manner with the plant communities characterizing the collection sites. The proportions of pistillate plants, total hermaphrodites, strong hermaphrodites, and weak hermaphrodites in collections from the northern forest floristic province in the northeastern part of the region were not significantly different from those of collections from the southwestern prairie-forest floristic region, although collections from the prairie-forest province were more variable for gender composition than populations from the northern forest province. Lack of staminate plants and increased percentages of hermaphrodite plants, relative to reports in the literature, suggest that the gender composition of F. virginiana populations in Minnesota has changed, perhaps as a result of introgression from hermaphroditic Fragaria ×ananassa or Fragaria vesca. Key words: Fragaria chiloensis, Fragaria vesca, Fragaria ×ananassa, dioecy, introgression, evolution.