Carnegiea

Carnegiea is a genus of cacti in the family Cactaceae. It is a monotypic genus, containing a single extant species, Carnegiea gigantea, commonly known as the saguaro. The genus was named in honor of the industrialist Andrew Carnegie, and the species epithet gigantea references its large size.

Carnegiea gigantea is native to the Sonoran Desert, occurring in the southwestern United States (primarily Arizona and parts of California) and northwestern Mexico (notably the state of Sonora). It is renowned for its tree-like form, with a tall, cylindrical trunk and upward-reaching arms that develop as the plant ages. Saguaros can reach heights of 9–12 meters or more, and their ribs can number two dozen or more. The cactus stores water in its tissues, enabling it to endure prolonged droughts. Growth is slow, and some individuals live for many decades or centuries.

Ecology and biology: Saguaros bloom in late spring, producing white, night-opening flowers that are pollinated mainly by bats, with moths and bees contributing. The edible fruit ripens in early summer and is used by wildlife and by people. Older saguaros create cavities that provide nesting sites for birds such as Gila woodpeckers and gilded flickers. The plant plays a key role in desert ecosystems and holds cultural significance for Indigenous peoples, including the Tohono O’odham, who harvest the fruit for food.

Conservation: The species is listed as Least Concern by major assessments, though it faces threats from extreme drought, climate change, and habitat disturbance in parts of its range. Some regions regulate removal of wild saguaros to protect populations.