Helianthus paradoxus (paradox sunflower, puzzle sunflower, Pecos sunflower) is a threatened species of sunflower found only in west Texas, Utah, and New Mexico salt marshes by the edges of inland salt lakes and salt flats. This species was added to the Endangered Species Act on October 20, 1999. It is found in spring seeps, wet meadows, pond margins, and stream courses. All these populations are dependent on natural groundwater deposits.