Methods for the production of new Adonis palaestina plants and plant populations with improved characteristics such as increased flower size, astaxanthin content, and/or reduced cardenolide content are provided. Also provided are an astaxanthin-containing Adonis oleoresin and methods of extracting astaxanthin and other ketocarotenoids from flowers of Adonis palaestina plants, while reducing non-ketocarotenoids and cardenolides.