In order to evaluate how fast intrapopulational genetic variability increases after colonization, morphological variation and isozyme diversity were studied in four populations of Saxifraga oppositifolia L. in an alpine valley of Central Switzerland. Three populations grew in natural habitats and were assumed to be long established. Another population was located on a 50‐year old roadside slope. This younger population showed the same level of morphological and genetic variability and diversity than did the older populations. The potential to inbreed admits single seed colonization in S. oppositifolia, and gene flow through pollen or seed and subsequent outbreeding may increase intrapopulational genetic diversity and variation with time. As a consequence, established populations of S. oppositifolia exhibit low genetic differentiation at the landscape level.