Morphological variation between geographically distant populations has long been recognized. The primary objective of this study was to test whether nonrandom shifts in morphology have occurred across a 150-year time span in two rare, endangered plant species Geum radiatum and Houstonia montana. During the last century the vegetation on Roan Mountain has undergone numerous environmental pressures that may have produced morphological shifts. A diverse suite of morphological characters was measured from both species. Characters included vegetative and reproductive structures. Herbarium specimens and direct field measurements were the sources of material used. Results indicated a significant increase in size across time in the majority of characters measured. Results of this study challenge standard taxonomic practices, present questions pertaining to the relationship between genetics and morphology, and raise issues concerning conservation and management strategies of endangered plant populations.