Helianthus paradoxus (Puzzle Sunflower) is a threatened species of sunflower found only in west Texas and New Mexico salt marshes. H. paradoxus is most likely a stable hybrid of H. annuus, the common sunflower, and H. petiolaris, and is more tolerant of salt than either parent species. H. paradoxus is found in areas with salinity levels ranging from 10–40 parts per thousand. Due to its ability to withstand such high levels of salt, H. paradoxus is considered to be a halophyte.
This species is also called the "Pecos sunflower".