The Worldwide Significance of Karyotypic Variation in Rosa Acicularis (rosaceae)

Evidence is provided which shows that there is a wider variation in karyotypes of Rosa acicularis subspecies seen within their ranges in North America (Rosa acicularis Lindl. subsp. sayi (Schwein.) W.H. Lewis and the Eurasian species (Rosa acicularis Lindl. subsp. acicularis) than was originally presumed. It is proposed that the evolution and distribution of these karyotypes into two distinct subspecies occurred following the closure of the Turgai strait when the climate radically changed within both continents. Their distributions are similar in that they are not only dependent upon the latitudes where they are found but on the ecology and climate that supports their growth. Parallel ethnobotanical and medicinal uses are also evident as is their value in horticulture, where especially in North America their genes for cold hardiness are being exploited. Concerns regarding how global warming may affect these various karyotypes are also discussed.