In the genus Viola, about 50 species are known to occur in Japan. As for those species distributed in various habitats, many inter-specific variations in life history traits have been reported. However, few studies have focused on intra-specific life history variations. Here, we focused on Viola brevistipulata var. brevistipulata, which shows isolated distribution range with various habitat conditions. We selected 10 populations in southwestern Hokkaido and marked 40 individual plants. The monitorings, mainly flowering and shoot phenology, of those marked individuals were conducted every 1-2 weeks at each population.

As a result, we found this species possesses two types of flower, i.e., chasmogamous (CH) and cleistogamous (CL) flower. In addition, the expression of these flower types was distinct among the populations. That is, there were populations, consisted of plants with only CH flowers, while the another ones produced CL flowers after CH flowers with longer longevity of the shoots. This phenomenon was observed even in the parapatric populations. The results suggest that there have been occurring life history variations, at least in breeding systems, among the populations of V. brevistipulata var. brevistipulata.