saguaro

Saguaro
Scientific classification
Kingdom:	Plantae
Division:	Magnoliophyta
Class:	Magnoliopsida
Order:	Caryophyllales
Family:	Cactaceae
Subfamily:	Cactoideae
Tribe:	Pachycereeae
Genus:	Carnegiea Britton & Rose
Species:	C. gigantea
Binomial name
Carnegiea gigantea Britton & Rose
Synonyms
Cereus giganteus Engelm.

The saguaro, pronounced /səˈwɑroʊ/ (Carnegiea gigantea), is a large, tree-sized cactus species in the monotypic genus Carnegiea. It is native to the Sonoran Desert in the U.S. state of Arizona, the Mexican state of Sonora, and an extremely small area of California, U.S. The saguaro blossom is the state flower of Arizona.

The common name saguaro came into the English language through the Spanish language, originating in the language of the Tohono O'odham native American nation.

Growth

Some saguaro are "crested" due to fasciation, instead of having arms.

Saguaros have a relatively long life span. They take up to 75 years to develop a side arm. The arms themselves are grown to increase the plant's reproductive capacity (more apices equal more flowers and fruit). The growth rate of saguaros is strongly dependent on precipitation; saguaros in drier western Arizona grow only half as fast as those in and around Tucson, Arizona. Some specimens may live for more than 150 years;^[1] the Champion Saguaro grows in Maricopa County, Arizona and is 13.8 meters (45.3 ft) tall with a girth of 3.1 meters (10 ft). They are also slow to propagate.

Spines

The spines on saguaro having a height less than 2 meters grow rapidly, up to a millimeter per day. When held up to the light or bisected, alternating light and dark bands transverse to the long axis of spines can be seen. These transverse bands have been correlated to daily growth. In columnar cacti, spines almost always grow from the apex of the plant and then cease to grow as they are moved to the side and the apex continues to grow upwards. Thus, the older spines are towards the base of a columnar cactus and newer spines are near the apex. Current studies are underway to examine the relationship of carbon and isotope ratios in the tissues of spines to the past climate and photosynthetic history of the plant.^[2]

Flowers

The night blooming flowers appear April through May and the sweet, ruby-colored fruit matures by late June. Each fruit can contain up to 2,000 seeds. Saguaro flowers are self incompatible and require a pollinator. A well-pollinated fruit will contain several thousand tiny seeds, and large quantities of pollen are required for pollination. The major pollinators are bats, primarily the lesser long-nosed bat, feeding on the nectar from the night-blooming flowers, which often remain open in the morning.

Nests

Gila woodpeckers, purple martins, house finches, and gilded flickers live inside holes in saguaros. Flickers excavate larger holes higher on the stem, penetrating the ribs which can stress or even kill the plant. These woodpeckers^[ambiguous] create new nest holes each season rather than reuse the old ones, leaving convenient nest holes for other animals, especially elf owls.

Relation to humans

Harming a saguaro in any manner, including cactus plugging, is illegal by state law in Arizona, and when houses or highways are built, special permits must be obtained to move or destroy any saguaro affected.

The ribs of the saguaro were used for construction and other purposes by Native Americans. A fine example can be seen in the roofing of the cloisters of the Mission San Xavier del Bac on the Tohono O'odham lands near Tucson, Arizona. The Seri people of northwestern Mexico used the plant which they call mojépe for a number of purposes.

The saguaro is often used as an emblem in commercials and logos that attempt to convey a sense of the southwest, even when the product has no connection to Arizona, or the Sonoran Desert. For instance, no saguaros are found within 250 miles (400 km) of El Paso, Texas, but the silhouette is found on the label of Old El Paso brand products. Though the geographic anomaly has lessened in recent years, Western films once enthusiastically placed saguaros Monument Valley of Arizona, New Mexico, and Texas. There are no wild saguaros anywhere in such western U.S. states as Texas, Colorado, Utah, New Mexico, or Nevada, nor in the high deserts of northern Arizona.

Gallery

Saguaro towering over a 5 ft 11 in (180 cm) man	Mature five armed in flower	Snow covered saguaro near Tucson, Arizona	Needles of a saguaro, Paradise Valley, AZ	Saguaro flowers, Scottsdale, Arizona
Saguaro "forest" near Tucson	The bare wooden ribs of a dead saguaro	Saguaro with nest holes	Looking up a saguaro	Saguaro in Scottsdale, Arizona
Sunset in Saguaro National Park	Unusually formed saguaro from Sonoran desert near Kino Bay	Inside a dead saguaro	Saguaro blooming

See also

• Arizona-Sonora Desert Museum

References

Notes

Bibliography

• Benson, L. (1981). The Cacti of Arizona. University of Arizona Press. ISBN 0-8165-0509-8.
• Felger, Richard; Mary B. Moser. (1985). People of the desert and sea: ethnobotany of the Seri Indians. Tucson: University of Arizona Press. 
• Drezner TD (2005) Saguaro (Carnegiea gigantea, Cactaceae) growth rate over its American range and the link to summer precipitation. Southwest Nat 50:65–68.

External links

Wikimedia Commons has media related to: Carnegiea

Look up saguaro in Wiktionary, the free dictionary.

• Flora of North America: Carnegiea gigantea
• Jepson Flora Project: Carnegiea gigantea
• Calphotos: Carnegiea gigantea
• USDA Plants Profile: Carnegiea gigantea
• AMNH Young Naturalist report