Naming a phantom – the quest to find the identity of Ulluchu, an unidentified ceremonial plant of the Moche culture in Northern Peru

The botanical identification of Ulluchu , an iconic fruit frequently depicted in the art of the pre-Columbian Moche culture that flourished from A.D. 100–800 on the Peruvian north coast, has eluded scientists since its documentation in ceramics in the 1930s. Moche fine-line drawings of Ulluchu normally depict seed-pods or seeds floating in the air in sacrificial scenes, associated with runners and messengers or intoxicated priests. It is a grooved, comma-shaped fruit with an enlarged calyx found mainly in fine-line scenes painted on Moche ceramics. The term first appeared without linguistic explanation in the work of pioneer Moche scholar Rafael Larco Hoyle, and the identification of the plant was seen as the largest remaining challenge in current archaebotany at the Peruvian North coast. The name Ulluchu seems to have been coined by Larco. According to his description, the name originated in the Virú River valley, and is supposedly of Mochica origin. However, there is no linguistic evidence that such a term indeed existed in the Mochica or Yunga language. We conclude that Ulluchu can be identified as a group of species of the genus Guarea (Meliaceae) based on morphological characteristics. In addition, the chemical composition of the plant's compounds supports the thesis that it was used in a sacrificial context to improve the extraction of blood from sacrificial victims. We also suggest that a ground preparation of Guarea seeds, when inhaled, may have been used as a hallucinogen. However, more detailed phytochemical research is needed to corroborate the latter hypothesis.