Crassula peduncularis and c. Saginoides (crassulaceae), newly naturalized in japan, and their genetic differences from c. aquatica

Recently, we found two species of Crassula newly introduced into central Japan. Based on their morphology, we identified them as Crassula peduncularis and C. saginoides, native to the New World. They closely resemble C. aquatica, which is indigenous to Japan. Here, we describe the morphological distinctions among the three species in detail. In addition, we examined genetic differences among the three species based on sequence variations in the nuclear ribosomal ITS region and three chloroplast intergenic regions. Although C. saginoides was considered to be an inland form of C. aquatica and had been treated as a synonym of C. aquatica, the degree of genetic differentiation was relatively large, suggesting that these two taxa should be considered to be independent species.