A study to determine whether or not the relatively high radioactivity of a natural area has produced detectable morphological effects on plants of the species Penstemon virens, a plant of rather plastic morphology, has been conducted in the Central City region of Colorado for over 2 years. While no differences in kinds of anomalies were found to exist between plants growing in the sites of highest and lowest radioactivity, the number of anomalies was greater in plants from sites of greatest radioactivity.