Takashi Shiga, and Aquatic Plant Research Team of Yamatogawa River Research Group (Project Y, Osaka Museum of Natural History), 2008. Geographic distributions of Veronica undulata and alien species, V. anagallis-aquatica, and their hybrids in Yamatogawa River system, central Japan. Bulletin of the Osaka Museum of Natural History 62: xx-xx. (in Japanese with English abstract)
We researched the geographic distribution and herbarium specimens of Veronica species (Schrophulariaceae): V. undulata (native species), V. anagallis-aquatica (alien species), and V. ×myriantha (hybrid between native and exotic species). We found 32 stands of V. undulata, and 71 stands of V. anagallis-aquatica. The two species were found sympatric at 20 stands, and V. ×myriantha was found at 2 sympatric stands (10%). The geographic range of V. anagallis-aquatica was wider than that of V. undulata. It is expected that sympatric stands will increase, and subsequently, V. anagallis-aquatica will continue to influence V. undulata ecologically and genetically by competition and hybridization.
alien species; geographic distribution; hybridization; Veronica undulata; Veronica anagallis-aquatica; Yamatogawa River system