Two Sterile Hybrids of Woodsia (Woodsiaceae) with Different Ploidy Found in Hokkaido, Japan

Abstract

Previous studies indicated that Woodsia subcordata has an allotetraploid origin resulting from the hybridization between W. ilvensis and W. polystichoides. In this study, several individuals of the genus Woodsia, which has no mature sporangia, were collected from Hokkaido, Japan. Based on DNA contents, nuclear and plastid DNA polymorphism, the sterile individuals were identified as diploid hybrids between W. ilvensis and W. polystichoides, or triploid hybrids between W. polystichoides and W. subcordata. To distinguish the hybrid of W. ilvensis × W. polystichoides from W. subcordata in Hokkaido, it is necessary to check whether sporangia are shrunken. On the other hand, W. polystichoides × W. subcordata is rather easy to distinguish from W. polystichoides and W. subcordata in having shallowly serrated pinnae and scales.