Adonis aestivalis, the summer pheasant's-eye, is a medicinal and ornamental plant. It is native to Europe but has been introduced elsewhere, such as the western and eastern parts of the United States. The specific epithet, aestivalis, is derived from Latin and means 'pertaining to the summer'.
Bailey, L. H. (2005). Manual of Gardening (Second Edition). Project Gutenberg Literary Archive Foundation.
Burke Museum of Natural History and Culture: Adonis aestivalis
Plants for a Future: Adonis aestivalis ...