We investigated the clonal structure, self-incompatibility, and number of seeds per fruit in Camellia rusticana, a Japanese endemic species, in comparison to the closely related C. japonica. Clonal propagation was more vigorous in C. rusticana than in C. japonica and the clonal structure of C. rusticana varied among populations. C. rusticana can maintain genets for extended periods, even in harsh environments such as high-altitude areas with considerable snow accumulation, because even a single surviving genet can propagate clonally. However, sexual reproduction (i.e., reproduction by seed) is advantageous for dispersal to distant suitable habitats. An artificial crossing test revealed high self-incompatibility in C. rusticana, as observed in C. japonica. In addition, the number of seeds per fruit was lower in C. rusticana than in C. japonica. Self-incompatibility in C. rusticana may play a role in production of high-quality seed, despite low seed production.
