Autor: Britton & Rose

A genus honouring the North American philanthropist of Scottish origin Andrew Carnegie (1835-1919) whose foundation financed, among others, the works of Britton & Rose (see portrait above, public domain).
Monospecific genus of giant massive and slow-growing plants, with thick, columnar, branched stems, with very close areoles.
Flowers open day and night, self sterile, appearing near the top of stems, funnel-shaped to bell-shaped, white, fragrant, scaly, mainly pollinated at night by bats (Antrozous pallidus, Choeronycteris mexicana, Leptonycteris curasoae, L. yerbabuenae), and during the day by turtledoves (Zenaida asiatica mearnsii, Z. macroura) and other birds (Auriparus flaviceps, Carpodacus mexicanas, Colaptes auratus, Icterus parisorum, Melanerpes uropygialis, minimoved Psaltriparus, Toxostoma curvirostre, etc.), also hummingbirds (Cynanthus latirostris, Calypte costae, Selasphorus rufus), as well as bees (Apis, Bombus, Megachile, Xylocopa) and Sphingideae (Hyles lineata). Fruits fleshy, juicy, with blood red pulp, dehiscent, splitting in three or four. Seeds rather small, ovate, shiny, dark brown to almost black. Dispersion of seeds provided by birds and ants.
The monotypic genus Carnegiea grows in the Sonoran desert in the United States and northern Mexico, on hillsides, in valleys, canyons, on rocky grounds, almost from sea level up to a maximum altitude of 2000 m. The rare spontaneous natural seedlings grows initially in the shade of shrubs (Simmondsia, Larrea etc.) or bushes (Ambrosia). They sometimes receive snow in winter, but such prolonged events may decimate part of the population if the frost and humidity persist.
Mexico (Sonora), USA (Arizona, California).

Currently only one recognised species:
– Carnegiea gigantea* (Engelm.) Britton & Rose 1908

References: "TAXONOMY of the CACTACEAE" -  ISBN 978-84-617-3723-9 (Vol. 1)