Castela is a genus of thorny shrubs and small trees in the family Simaroubaceae, order Sapindales. Members of this genus are native to the Americas, with a concentration in tropical regions. The genus is dioecious, meaning individual plants produce either male or female flowers but not both. There are 17 accepted species, including the well-known crucifixion thorn (Castela emoryi) of the North American deserts, goatbush (Castela erecta) widespread in the Caribbean and Gulf Coast, and the Galápagos bitterbush (Castela galapageia). The plants are generally armed with spines and produce small flowers. The genus was named in honour of René Richard Louis Castel, a French naturalist.
Etymology
The genus name Castela honours René Richard Louis Castel (1758–1832), a French naturalist, poet, and professor. The name was published by the French botanist Pierre Jean François Turpin.
Distribution
Castela is native to the Americas, with species distributed from the southwestern United States and northern Mexico south through the Caribbean, Central America, and into South America, as well as the Galápagos Islands. The genus is most diverse in tropical and subtropical regions, particularly the Caribbean and Mexico.
Taxonomy
Castela belongs to the family Simaroubaceae within the order Sapindales. Wikipedia lists 17 accepted species, though GBIF records only 2 descendants under this genus, suggesting incomplete taxonomic coverage in GBIF for this group. The genus is dioecious and characterized by thorny, woody growth. Notable species include Castela emoryi (crucifixion thorn) of the Sonoran Desert, Castela erecta (goatbush) of the Caribbean basin, and Castela galapageia (bitterbush) endemic to the Galápagos.
Ecology
Castela species are dioecious, with separate male and female plants — a reproductive strategy that requires cross-pollination. They grow as thorny shrubs or small trees, typically in arid to semi-arid tropical and subtropical habitats. The thorns likely serve as a defense against herbivory in the seasonally dry environments the genus occupies.
