Schoenocrambe barnebyi (syn. Hesperidanthus barnebyi) is a rare species of flowering plant in the mustard family known by the common names Barneby reed-mustard, Syes Butte plainsmustard, and Barneby thelypody. It is endemic to Utah in the United States, where it is known only from Emery and Wayne Counties. It is threatened by habitat degradation and destruction. It is federally listed as an endangered species of the United States.