Abstract
The perennial herbaceous plant Amsonia elliptica has been designated an endangered species (near threatened, NT) in Japan due to its recent rapid decline in abundance and decreased habitat patches, but there are no precise locality records and habitat characteristics, which are essential for conservation. We first compiled distribution records for A. elliptica from a variety of sources, such as herbarium specimens, publications, and personal information, and then conducted a field survey to examine the numbers of shoots at each locality and the habitat characteristics. A total of 180 locality records were obtained for 38 prefectures from Hokkaido to Miyazaki Prefecture. Of these, we confirmed extinction in seven prefectures, but could not confirm either presence or absence in seven prefectures. Integrated locality records supplemented with our field survey suggested that habitats affected by periodic flooding and high groundwater levels, such as lakefronts, riverbeds, small valley bottoms, and valley slopes, were suitable habitats, and reduced natural disturbance due to flood-control practices and artificial modification of the original topography caused deterioration of habitat suitable for A. elliptica.
