Proboscidea is a genus of flowering plants in the family Martyniaceae, within the order Lamiales. Commonly known as devil's claw, devil's horn, ram's horn, or unicorn plant, the genus contains around five species native to arid and semi-arid regions of the Americas, particularly the southwestern United States and Mexico.
The genus is most recognizable by its unusual seed pods: as the pods dry and harden, they split into two long curved horns or "claws" that hook onto the feet and legs of passing animals, which then carry the pods away and grind them open as they walk, dispersing the seeds. This zoochorous dispersal mechanism is the origin of the common names devil's claw and unicorn plant.
Among the best-known species are Proboscidea louisianica (ram's horn), Proboscidea parviflora (devil's claw), Proboscidea althaeifolia (desert unicorn plant), Proboscidea sabulosa (dune unicorn plant), and Proboscidea spicata (New Mexico unicorn plant). The genus has long been significant to Indigenous peoples of the American Southwest: the Tohono O'odham have cultivated P. parviflora and selectively bred varieties with especially long claws for use in traditional black-and-white basket weaving, and both the Tohono O'odham and the Hia C-eḍ O'odham harvest the oil-rich seeds as a food source. The immature fruits of all species are edible and can be prepared similarly to okra.
Etymology
The genus name Proboscidea derives from the Greek proboskis (elephant's trunk or snout), a reference to the long, curved beak-like projection of the developing seed pod. The same root gives the mammal order Proboscidea (elephants) its name.
Distribution
Species of Proboscidea are native to the Americas, with the greatest diversity in the southwestern United States and Mexico. Individual species occupy a range of dry habitats including desert flats, dunes, roadsides, and disturbed agricultural ground.
Ecology
The hooked, woody seed pods of Proboscidea are an adaptation for epizoochorous (animal-carried) seed dispersal. The curved horns latch onto the hooves and feet of large mammals, and the pods are mechanically broken open as the animal walks, releasing the seeds. This strategy is particularly effective in open desert and grassland environments where large herbivores move across wide areas.
Cultural Uses
Proboscidea species have been important to Indigenous cultures of the American Southwest for generations. The Tohono O'odham and Chemehuevi peoples weave the long black claws of dried P. parviflora pods into baskets, creating distinctive dark geometric designs; the Tohono O'odham have selectively cultivated varieties with unusually long claws specifically for this purpose. The Tohono O'odham and Hia C-eḍ O'odham also eat the seeds, which are a significant source of dietary oils. Immature green fruits of all species are edible and can be steamed and eaten much like okra. P. parviflora has also been used as a folk remedy for rheumatism.
