Feb 15 2020
With its tall, columnar shape and upward-bending branches, the cactus we know as the saguaro is a defining plant species of the Sonoran Desert of southern Arizona and northern Mexico. Saguaros, which can live to be 150-200 years old, are beautifully designed for their arid habitat-when it rains, the water is directed down the grooves in the columnar plant body directly to the very shallow roots that extend only about two feet below ground. White in color, the night-blooming flowers are produced near the tops of the stems and branches, pollinated by bats. Other animals such as birds, reptiles, mammals, and insects depend on the saguaro for food and shelter. Native people such as Tohono O'odham harvest saguaro fruits to make wine and jam.
The saguaro was first described as Cereus giganteus by George Engelmann, the nation’s first expert in cacti, and founding botanist of the Missouri Botanical Garden. His description appears to be based on observations by Charles Parry (1823-1890). Parry was surgeon, botanist, and explorer on the U.S. Mexico Boundary Survey that explored the southwest between 1848 and 1853. Parry made extensive collections on this expedition (see an example below), but apparently he did not make a specimen of the saguaro.
In the course of a later study of the cacti, New York Botanical Garden founder Nathaniel Britton and his collaborator Joseph N. Rose from the National Herbarium at the Smithsonian decided that the saguaro belonged in its own genus. They chose to name it Carnegiea in honor of industrialist and philanthropist Andrew Carnegie (1835-1919). On 2 November, 1902 Britton wrote to Andrew Carnegie asking his permission to give his name to:
“a new genus of Cactuses, based on the Giant Cactus of Arizona and northern Mexico.…we have thought it peculiarly fitting that the Giant Cactus should bear your name”.
Mr. Carnegie’s secretary responded on Carnegie’s behalf on 5 November:
“Mr Carnegie has yours of November 2nd and asks me to say he is greatly honored by the proposal and will do his best to live up to it.”
Naming the saguaro for Carnegie was “peculiarly fitting” for a variety of reasons. Carnegie (along with Cornelius Vanderbilt and J. P. Morgan) was instrumental in the founding of the New York Botanical Garden. Also, funds from Carnegie’s vast fortune were used to establish the Desert Botanical Laboratory, founded near Tucson in 1903 to study how plants survive and thrive in arid habitats. The first director of the Desert Botanical Laboratory was D. T. MacDougal (1865-1958) who previously had been Assistant Director at the New York Botanical Garden, and remained a close collaborator of Britton after he left New York for Arizona. Finally, it was the Carnegie Institute of Washington that later published Britton and Rose’s four volume monograph of the Cactaceae (1919-1923).
Nathaniel and Elizabeth Britton established NYBG to be parallel in breadth and scope to the Royal Botanic Gardens at Kew, and to represent an American approach to study of plants. Britton and Rose’s study of the Cactaceae, which grows natively only in the Americas, was meant to exemplify this approach-which included not only a revision of the existing taxonomy of the family, but also creation of a living collection in the Garden’s Conservatory for public display. Through Britton’s efforts, the Garden’s living and herbarium collections of cacti quickly became among the largest in the world and generations of New York City children have seen their first saguaro in the American Desert House of the Enid A. Haupt Conservatory.
The saguaro is not listed as threatened or endangered, but Arizona has strict rules about the harvesting of fruits and the collection or destruction of plants. International transport of the saguaro and all cacti is strictly controlled by CITES (the Convention on International Trade in Endangered Species). Thousands of saguaro live within the boundaries of Saguaro National Park, which covers about 150 square miles in two locations near Tucson. Although relatively well protected from direct destruction, the saguaro does face threats from temperature rise and invasive species, such as the buffelgrass that crowds out young saguaro and increases the risks of fires.
