Abstract
We explored the current status of sexual reproduction and clonal growth in six populations of the common reed, Phragmites australis, in eastern parts of Shiga Prefecture and Mizoroga-ike pond in Kyoto Prefecture. At each population, we determined genets using six SSR markers and investigated seed set and ploidy levels. Genet diversity was high in four populations, three of which also had high seed set. In contrast, two other populations were composed of a single genet and had very low seed set. Similarly low genetic diversity and seed set has been previously reported for some large populations surrounding Lake Biwa and Naiko. We germinated seedlings to determine ploidy levels for the populations and found tetraploid, hexaploid, and octaploid individuals. Hexaploid individuals may be a result of mating between individuals of different ploidy levels. We found no seedlings, even in populations composed of several genets, suggesting inappropriate environmental conditions for seedlings, such as flooding, high water levels and lack of open patches. This suggests that these populations are maintained by prolonged clonal growth, not by the recruitment and establishment of seeds.
