Rauvolfia sandwicensis, the devil's-pepper,[1] also known as hao in the Hawaiian language, is a species of flowering plant in the milkweed family, Apocynaceae, that is endemic to Hawaii.

[3] The Hao is one of the few rare species of plant in Hawai’i along with the Antidesma pulvinatum or Hame, Mvoporum sandwicense or Naio, Reynoldsia sandwicensis or ‘Ohe, Santalum paniculatum or ‘Iliahi, Senna gaudichaudii or Kolomona, and Xylosma hawaiiense or Maua.

Within all the Hawaiian Islands by Kaho’olawe, the Hao grows in dry- or shrub-land forests within lower elevations as the tree is part of the Dogbane or Apocynaceae family.

[4] The Hao does not have any known religious or cultural significance, or usefulness as forage, food, medicine, or shelter, for the Hawaiian people.

[5] During 1957, a study was conducted on the Hao to determine the types of alkaloid compounds within the make-up of the tree.