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The saguaro (, ) (''Carnegiea gigantea'') is a tree-like
cactus A cactus (, or less commonly, cactus) is a member of the plant family Cactaceae, a family comprising about 127 genera with some 1750 known species of the order Caryophyllales. The word ''cactus'' derives, through Latin, from the Ancient Gree ...
species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...
in the
monotypic In biology, a monotypic taxon is a taxonomic group (taxon) that contains only one immediately subordinate taxon. A monotypic species is one that does not include subspecies or smaller, infraspecific taxa. In the case of genera, the term "unispe ...
genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nom ...
''Carnegiea'' that can grow to be over tall. It is native to the
Sonoran Desert The Sonoran Desert ( es, Desierto de Sonora) is a desert in North America and ecoregion that covers the northwestern Mexican states of Sonora, Baja California, and Baja California Sur, as well as part of the southwestern United States (in Ariz ...
in
Arizona Arizona ( ; nv, Hoozdo Hahoodzo ; ood, Alĭ ṣonak ) is a state in the Southwestern United States. It is the 6th largest and the 14th most populous of the 50 states. Its capital and largest city is Phoenix. Arizona is part of the Fou ...
, the Mexican state of Sonora, and the
Whipple Mountains The Whipple Mountains ( Mojave: Avii Kur'utat; Chemehuevi: Wiyaatuʷa̱) are located in eastern San Bernardino County, California. They are directly west of the Colorado River, Parker Dam, and Lake Havasu; south of Needles, California; north of ...
and
Imperial County Imperial Count (german: Reichsgraf) was a title in the Holy Roman Empire. In the medieval era, it was used exclusively to designate the holder of an imperial county, that is, a fief held directly ( immediately) from the emperor, rather than from ...
areas of California. The saguaro blossom is the state wildflower of Arizona. Its scientific name is given in honor of
Andrew Carnegie Andrew Carnegie (, ; November 25, 1835August 11, 1919) was a Scottish-American industrialist and philanthropist. Carnegie led the expansion of the American steel industry in the late 19th century and became one of the richest Americans i ...
. In 1994,
Saguaro National Park Saguaro National Park is an American national park in Pima County, southeastern Arizona. The park consists of two separate areas—the Tucson Mountain District (TMD) about west of the city of Tucson and the Rincon Mountain District (RMD) about ...
, near
Tucson, Arizona , "(at the) base of the black ill , nicknames = "The Old Pueblo", "Optics Valley", "America's biggest small town" , image_map = , mapsize = 260px , map_caption = Interactive map ...
, was designated to help protect this species and its habitat. Saguaros have a relatively long lifespan, often exceeding 150 years. They may grow their first side arm around 75–100 years of age, but some never grow any arms. Arms are developed to increase the plant's reproductive capacity, as more apices lead to more
flower A flower, sometimes known as a bloom or blossom, is the reproductive structure found in flowering plants (plants of the division Angiospermae). The biological function of a flower is to facilitate reproduction, usually by providing a mechani ...
s and fruit. A saguaro can absorb and store considerable amounts of rainwater, visibly expanding in the process, while slowly using the stored water as needed. This characteristic enables the saguaro to survive during periods of drought. It is a keystone species, and provides food and habitat to a large number of species. Saguaros have been a source of food and shelter for humans for thousands of years. Their sweet red fleshed fruits are turned into syrup by native peoples, such as the
Tohono Oʼodham The Tohono Oʼodham (; Oʼodham: ) are a Native American people of the Sonoran Desert, residing primarily in the U.S. state of Arizona and the northern Mexican state of Sonora. The federally recognized tribe is known in the United States as t ...
and Pima. Their ribs are used as building materials in the wood-poor deserts. The saguaro cactus is a common image in Mexican culture and American Southwest films.


Description

The saguaro is a columnar
cactus A cactus (, or less commonly, cactus) is a member of the plant family Cactaceae, a family comprising about 127 genera with some 1750 known species of the order Caryophyllales. The word ''cactus'' derives, through Latin, from the Ancient Gree ...
that grows notable
branch A branch, sometimes called a ramus in botany, is a woody structural member connected to the central trunk of a tree (or sometimes a shrub). Large branches are known as boughs and small branches are known as twigs. The term ''twig'' usually ...
es, usually referred to as arms. Over 50 arms may grow on one plant, with one specimen having 78 arms. Saguaros grow from tall, and up to in diameter. They are slow growing, but routinely live 150 to 200 years. They are the largest cactus in the United States. The growth rate of this cactus is strongly dependent on
precipitation In meteorology, precipitation is any product of the condensation of atmospheric water vapor that falls under gravitational pull from clouds. The main forms of precipitation include drizzle, rain, sleet, snow, ice pellets, graupel and hail. ...
; saguaros in drier western Arizona grow only half as fast as those in and around
Tucson , "(at the) base of the black ill , nicknames = "The Old Pueblo", "Optics Valley", "America's biggest small town" , image_map = , mapsize = 260px , map_caption = Interactive map ...
. Saguaros grow slowly from seed, and may be only tall after two years. Cuttings rarely root, and when they do, they do not go through the juvenile growth phase, which gives a different appearance. the ''
National Register of Champion Trees The National Register of Champion Trees is a list of the largest tree specimens found in the United States as reported to American Forests by the public. A tree on this list is called a National Champion Tree. The National Register of Champion Tr ...
'' listed the largest known living saguaro in the United States in
Maricopa County Maricopa County is in the south-central part of the U.S. state of Arizona. As of the 2020 census, the population was 4,420,568, making it the state's most populous county, and the fourth-most populous in the United States. It contains about ...
, Arizona, measuring high with a girth of ; it has an estimated age of 200 years and survived damage in the 2005 Cave Creek Complex Fire. The tallest saguaro ever measured was an armless specimen found near
Cave Creek, Arizona Cave Creek is a town in Maricopa County, Arizona, United States. It is part of the Phoenix metropolitan area. As of the 2020 census, the population of the town was 4,892. History Cave Creek was settled in 1870 by soldiers on horseback from Fo ...
. It was in height before it was toppled in 1986 by a windstorm. Saguaros are
stem succulent Stem succulents are fleshy succulent columnar shaped plants which conduct photosynthesis mainly through their stems rather than their leaves.Frerea indica, a Stem Succulent CAM Plant with Deciduous C₃ Leaves, Otto L. Lange and Margit Zuber, Oec ...
s and can hold large amounts of water; when rain is plentiful and the saguaro is fully hydrated, it can weigh between . Saguaros have a very large root network that can extend up to , and long taproots of up to deep. Saguaros may take between 20 and 50 years to reach a height of . Individual stomatal guard cells and medulla cells can live and function for as long as 150 years, possibly the longest living of all cells, except possibly nerve cells in some tortoises. As a cactus, it uses
crassulacean acid metabolism Crassulacean acid metabolism, also known as CAM photosynthesis, is a carbon fixation pathway that evolved in some plants as an adaptation to arid conditions that allows a plant to photosynthesize during the day, but only exchange gases at night. ...
photosynthesis, which confers high levels of
water-use efficiency Water-use efficiency (WUE) refers to the ratio of water used in plant metabolism to water lost by the plant through transpiration. Two types of water-use efficiency are referred to most frequently: * photosynthetic water-use efficiency (also cal ...
. This allows the saguaro to only transpire at night, minimizing daytime water loss. A saguaro without arms is called a "spear". Some saguaros grow in rare formations called a cristate, or "crested" saguaro. This growth formation is believed to be found in one in roughly 10,000 saguaros, with 2743 known crested saguaros documented. The crest formation, caused by fasciation, creates a seam of abnormal growth along the top or top of the arm of the saguaro.


Ribs

Inside the saguaro, many "ribs" of wood form something like a skeleton, with the individual ribs being as long as the cactus itself and up to a few centimeters in diameter. The rib wood itself is also relatively dense, with dry ribs having a solid density around , which made the ribs useful to indigenous peoples as a building material. While the ribs of dead plants are not protected by the Arizona native plant law, the Arizona Department of Agriculture has released a memo discussing when written permission is needed before harvesting them because of the importance of the decomposition of cactus remains in maintaining desert soil fertility. The composition of the ribs is similar to that of hardwoods.


Spines

The spines on a saguaro are extremely sharp and can grow to long, and up to per day. When held up to the light or bisected, alternating light and dark bands transverse to the long axis of spines are visible. These bands have been correlated to daily growth. In columnar cacti, spines almost always grow in areoles that originate at the apex of the plant. A spine stops growing in its first season. Areoles are moved to the side and the apex continues to grow upward. Thus, older spines are toward the base of a columnar cactus and newer spines are near the apex. Studies are underway to examine the relationship of carbon and oxygen
isotope Isotopes are two or more types of atoms that have the same atomic number (number of protons in their nuclei) and position in the periodic table (and hence belong to the same chemical element), and that differ in nucleon numbers (mass numb ...
ratios in the tissues of spines of an individual to its climate and photosynthetic history (
acanthochronology Acanthochronology is the study of cactus spines or ''Euphorbia'' thorns grown in time ordered sequence (i.e. in series). Physical, morphological or chemical characteristics and information about the relative order or absolute age of the spines or ...
). The spines may cause significant injury to animals; one paper reported that a
bighorn sheep The bighorn sheep (''Ovis canadensis'') is a species of sheep native to North America. It is named for its large horns. A pair of horns might weigh up to ; the sheep typically weigh up to . Recent genetic testing indicates three distinct subspec ...
skull had been penetrated by a saguaro spine after the sheep collided with a saguaro. They can also cause severe injury to humans, being as sharp and nearly as strong as steel needles. Their long, unbarbed nature means that partially embedded spines can be easily removed, but their relative length can complicate injuries. The spines can puncture deeply, and if broken off, can leave splinters of spine deep in the tissue that can be difficult to remove. Fully embedded spikes are also difficult to remove. Such injuries do not usually result in infection, though, as the cactus spines are generally
aseptic Asepsis is the state of being free from disease-causing micro-organisms (such as pathogenic bacteria, viruses, pathogenic fungi, and parasites). There are two categories of asepsis: medical and surgical. The modern day notion of asepsis is deri ...
. However, spines that remain embedded may cause inflammatory granuloma.


Flowers

The white, waxy flowers appear in April through June, opening well after sunset and closing in midafternoon. They continue to produce nectar after sunrise. Flowers are
self-incompatible Self-incompatibility (SI) is a general name for several genetic mechanisms that prevent self-fertilization in sexually reproducing organisms, and thus encourage outcrossing and allogamy. It is contrasted with separation of sexes among individuals ...
, thus requiring cross-pollination. Large quantities of pollen are required for complete pollination because many ovules are present. This pollen is produced by the extremely numerous stamens, which in one notable case totaled 3,482 in a single flower. A well-pollinated fruit contains several thousand tiny seeds. Pollination is considered relatively generalized in that multiple species can produce effective pollination when some populations are excluded. Main pollinators are
honey bee A honey bee (also spelled honeybee) is a eusocial flying insect within the genus ''Apis'' of the bee clade, all native to Afro-Eurasia. After bees spread naturally throughout Africa and Eurasia, humans became responsible for the current cosm ...
s, bats, and
white-winged dove The white-winged dove (''Zenaida asiatica'') is a dove whose native range extends from the Southwestern United States through Mexico, Central America, and the Caribbean. They are large for doves, and can be distinguished from similar doves by th ...
s. In most, but not all studies, diurnal pollinators contributed more than nocturnal ones. Honey bees were the greatest contributors. Other diurnal pollinators are birds such as
Costa's hummingbird Costa's hummingbird (''Calypte costae'') is a bird species in the hummingbird family Trochilidae. It breeds in the arid region of the southwest United States and northwest Mexico; it winters in western Mexico. Taxonomy Costa's hummingbird was f ...
, the
black-chinned hummingbird The black-chinned hummingbird (''Archilochus alexandri'') is a small hummingbird occupying a broad range of habitats. It is migratory, spending winter as far south as Mexico. Taxonomy A hybrid between this species and Anna's hummingbird was ca ...
, the broad-billed hummingbird, the
hooded oriole The hooded oriole (''Icterus cucullatus'') is a medium-sized New World oriole. The male of this species ranges in color from a bright orange to a paler yellow, with a black back, face, tail and bib, with the wing containing two white bars. The fe ...
, Scott's oriole, the
Gila woodpecker The Gila woodpecker (''Melanerpes uropygialis'') is a medium-sized woodpecker of the desert regions of the southwestern United States and western Mexico. In the U.S., they range through southeastern California, southern Nevada, Arizona, and New M ...
, the
gilded flicker The gilded flicker (''Colaptes chrysoides'') is a large-sized woodpecker (mean length of ) of the Sonoran, Yuma, and eastern Colorado Desert regions of the southwestern United States and northwestern Mexico, including all of Baja California, ex ...
, the
verdin The verdin (''Auriparus flaviceps'') is a species of penduline tit. It is the monotypic, only species in the genus ''Auriparus'' and the only representative of the old world family Remizidae to be found in North America. Taxonomy The verdin ...
, and the
house finch The house finch (''Haemorhous mexicanus'') is a bird in the finch family Fringillidae. It is native to western North America and has been introduced to the eastern half of the continent and Hawaii. This species and the other two American rosefi ...
according to studies that examined the relative contributions of diurnal pollinators. The primary nocturnal pollinator is the lesser long-nosed bat, feeding on the nectar. Several floral characteristics are geared toward bat pollination (
chiropterophily Pollination syndromes are suites of flower traits that have evolved in response to natural selection imposed by different pollen vectors, which can be abiotic (wind and water) or biotic, such as birds, bees, flies, and so forth through a process c ...
): nocturnal opening of the flowers, nocturnal maturation of pollen, very rich nectar, position high above ground, durable blooms that can withstand a bat's weight, and fragrance emitted at night. Claw marks on the flower indicate pollination by a bat. Flowers grow long, and are open for less than 24 hours. Since they form only at the top of the plant and the tips of branches, saguaros growing numerous branches is reproductively advantageous. Flowers open sequentially, with plants averaging four open flowers a day over a bloom period lasting a month. In Southern Arizona, saguaros begin flowering around May 3 and peak on June 4. A decline in bat populations causes more daytime flower openings, which favors other pollinators.


Fruit

The ruby red fruits are long and ripen in June, each containing around 2,000 seeds, plus sweet, fleshy connective tissue. The fruits are often out of reach and are harvested using a pole (made of two or three saguaro ribs) long, to the end of which cross-pieces, which can be made of saguaro rib, catclaw, or
creosote bush ''Larrea tridentata'', called creosote bush and greasewood as a plant, chaparral as a medicinal herb, and ''gobernadora'' (Spanish for "governess") in Mexico, due to its ability to secure more water by inhibiting the growth of nearby plants. In S ...
, are attached. This pole is used to hook the fruits or knock them free. Saguaro seeds are small and short-lived. Although they germinate easily, predation and lack of moisture prevent all but about 1% of seeds from successful germination. Seeds must wait 1214 months before germination; lack of water during this period drastically reduces seedling survival. The existence of nurse plants is critical to seedling establishment. Palo verde trees and triangle bursage represent important nurse species. They act by regulating temperature extremes, increasing soil nutrients, and reducing
evapotranspiration Evapotranspiration (ET) is the combined processes by which water moves from the earth’s surface into the atmosphere. It covers both water evaporation (movement of water to the air directly from soil, canopies, and water bodies) and transpi ...
, among others. While nurse plants reduce summer temperature maxima by as much as , they are more important in raising winter minimum temperatures as extended frosts limit the range of saguaros. Native American Indians of the Southwest would make bread from the ground seeds of saguaro.


Genome

The saguaro
genome In the fields of molecular biology and genetics, a genome is all the genetic information of an organism. It consists of nucleotide sequences of DNA (or RNA in RNA viruses). The nuclear genome includes protein-coding genes and non-coding g ...
is around 1 billion base pairs long. Sequencing has revealed that the genome of the saguaro's chloroplast is the smallest known among nonparasitic flowering plants. Like several other highly specialized plant taxa, such as the carnivorous '' Genlisea'' and parasitic ''
Cuscuta ''Cuscuta'' (), commonly known as dodder or amarbel, is a genus of over 201 species of yellow, orange, or red (rarely green) parasitic plants. Formerly treated as the only genus in the family Cuscutaceae, it now is accepted as belonging in the ...
'', the saguaro has lost the ''ndh'' plastid genes, which codes for production of NADPH dehydrogenase pathway, but unlike those taxa, the saguaro remains fully
autotroph An autotroph or primary producer is an organism that produces complex organic compounds (such as carbohydrates, fats, and proteins) using carbon from simple substances such as carbon dioxide,Morris, J. et al. (2019). "Biology: How Life Wo ...
ic; i.e. it does not eat or steal part of its food. The saguaro is remarkable for the scale and completeness of gene loss; essentially no traces of the 11 ''ndh'' genes remain in the plastid. The genes appear to have been copied to the
nuclear DNA Nuclear DNA (nDNA), or nuclear deoxyribonucleic acid, is the DNA contained within each cell nucleus of a eukaryotic organism. It encodes for the majority of the genome in eukaryotes, with mitochondrial DNA and plastid DNA coding for the rest. I ...
and mitochondrial DNA, but those copies are non-functional. How the saguaro thrives in a high stress environment without working copies of this fairly important gene remains unknown, but it is possible that the functions of the ''ndh'' genes have been taken on by another pathway.


Taxonomy

''Carnegiea gigantea'' is the only species in the monotypic genus ''Carnegiea''. The first description of the species was made by
William H. Emory William Hemsley Emory (September 7, 1811 – December 1, 1887) was a prominent American surveyor and civil engineer in the 19th century. As an officer in the U.S. Army Corps of Topographical Engineers he specialized in mapping the United State ...
in 1848, during his surveys along the pre- Gadsden Purchase United States-Mexican border. This description allowed cactus expert George Engelmann to formally name it, during his work on the
United States and Mexican Boundary Survey The United States and Mexican Boundary Survey (1848–1855) determined the border between the United States and Mexico as defined in the Treaty of Guadalupe Hidalgo, which had ended the Mexican–American War. The results of the survey were publis ...
, published in 1859. The next major taxonomic treatment came from ''
The Cactaceae ''The Cactaceae'' is a monograph on plants of the cactus family written by the American botanists Nathaniel Lord Britton and Joseph Nelson Rose and published in multiple volumes between 1919 and 1923. It was landmark study that extensively reorg ...
'', the seminal work on cactus by
Nathaniel Lord Britton Nathaniel Lord Britton (January 15, 1859 – June 25, 1934) was an American botanist and taxonomist who co-founded the New York Botanical Garden in the Bronx, New York. Early life Britton was born in New Dorp in Staten Island, New York to Jasp ...
and
Joseph Nelson Rose Joseph Nelson Rose (January 11, 1862 – May 4, 1928) was an American botanist. He was born in Union County, Indiana. His father died serving during the Civil War when Joseph Rose was a young boy. He later graduated from high school in Libert ...
. What
tribe The term tribe is used in many different contexts to refer to a category of human social group. The predominant worldwide usage of the term in English is in the discipline of anthropology. This definition is contested, in part due to confli ...
''Carnegiea gigantea'' belongs to is a matter of taxonomic dispute. A molecular analysis of the cactus family in 2010 placed the saguaro in the Echinocereinae. The ARS
Germplasm Resources Information Network Germplasm Resources Information Network or GRIN is an online USDA National Genetic Resources Program software project to comprehensively manage the computer database for the holdings of all plant germplasm collected by the National Plant Germpl ...
places it in the
Echinocereeae The Echinocereeae are a tribe of cacti in the subfamily Cactoideae. Since 2006, the tribe has included the former tribe Pachycereeae in many treatments of cactus classification. The exact circumscription of the tribe has been subject to considera ...
. The generic name honors businessman and philanthropist
Andrew Carnegie Andrew Carnegie (, ; November 25, 1835August 11, 1919) was a Scottish-American industrialist and philanthropist. Carnegie led the expansion of the American steel industry in the late 19th century and became one of the richest Americans i ...
. The specific epithet ''gigantea'' refers to its formidable size.


Distribution and habitat

Saguaros are
endemic Endemism is the state of a species being found in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also found else ...
to the
Sonoran Desert The Sonoran Desert ( es, Desierto de Sonora) is a desert in North America and ecoregion that covers the northwestern Mexican states of Sonora, Baja California, and Baja California Sur, as well as part of the southwestern United States (in Ariz ...
and are found primarily in western Sonora in Mexico, and in southern and portions of western
Arizona Arizona ( ; nv, Hoozdo Hahoodzo ; ood, Alĭ ṣonak ) is a state in the Southwestern United States. It is the 6th largest and the 14th most populous of the 50 states. Its capital and largest city is Phoenix. Arizona is part of the Fou ...
in the US. There are only 30 known wild plants found in southeastern California. Elevation is a limiting factor to its environment, as the saguaro is sensitive to extended frost or cold temperatures. No confirmed specimens of wild saguaros have been found anywhere in
Nevada Nevada ( ; ) is a state in the Western region of the United States. It is bordered by Oregon to the northwest, Idaho to the northeast, California to the west, Arizona to the southeast, and Utah to the east. Nevada is the 7th-most extensive, ...
,
New Mexico ) , population_demonym = New Mexican ( es, Neomexicano, Neomejicano, Nuevo Mexicano) , seat = Santa Fe , LargestCity = Albuquerque , LargestMetro = Tiguex , OfficialLang = None , Languages = English, Spanish ( New Mexican), Navajo, Ke ...
,
Texas Texas (, ; Spanish: ''Texas'', ''Tejas'') is a state in the South Central region of the United States. At 268,596 square miles (695,662 km2), and with more than 29.1 million residents in 2020, it is the second-largest U.S. state by ...
,
Colorado Colorado (, other variants) is a state in the Mountain states, Mountain West subregion of the Western United States. It encompasses most of the Southern Rocky Mountains, as well as the northeastern portion of the Colorado Plateau and the wes ...
,
Utah Utah ( , ) is a state in the Mountain West subregion of the Western United States. Utah is a landlocked U.S. state bordered to its east by Colorado, to its northeast by Wyoming, to its north by Idaho, to its south by Arizona, and to it ...
, nor in the high deserts of northern Arizona. The northern limits of their range are the
Hualapai Mountains The Hualapai Mountains are a mountain range located in Mohave County, east of Kingman, Arizona. Rising up to 8,417 feet at its highest peak, the higher elevations of the Hualapai Mountains support Madrean Sky Island habitats, and are host to ...
in Arizona. They are the northernmost columnar cacti in the Americas.


Ecology

The saguaro is a keystone species, and provides food, shelter, and protection to hundreds of other species. Every stage of the saguaro's life sustains a significant number of species, from seedling to after its death.


As food

The saguaro provides voluminous amounts of pollen, nectar, and fruits. The fruits are eaten by the
white-winged dove The white-winged dove (''Zenaida asiatica'') is a dove whose native range extends from the Southwestern United States through Mexico, Central America, and the Caribbean. They are large for doves, and can be distinguished from similar doves by th ...
and ants, so that seeds rarely escape to germinate. White-winged doves are important pollinators, visiting blooms more often than any other bird species. For desert white-winged doves, 60% or more of their diet is saguaro-based. Their breeding cycle coincides with that of the saguaro blooming.


Nests

Gila woodpecker The Gila woodpecker (''Melanerpes uropygialis'') is a medium-sized woodpecker of the desert regions of the southwestern United States and western Mexico. In the U.S., they range through southeastern California, southern Nevada, Arizona, and New M ...
s and
gilded flicker The gilded flicker (''Colaptes chrysoides'') is a large-sized woodpecker (mean length of ) of the Sonoran, Yuma, and eastern Colorado Desert regions of the southwestern United States and northwestern Mexico, including all of Baja California, ex ...
s create holes in the cactus to make nests, which are later used by other birds, such as
elf owl The elf owl (''Micrathene whitneyi'') is a small grayish-brown owl about the size of a sparrow found in the Southwestern United States, central Mexico, and the Baja California peninsula. It has pale yellow eyes highlighted by thin white "eyebrow ...
s, purple martins, and
house finch The house finch (''Haemorhous mexicanus'') is a bird in the finch family Fringillidae. It is native to western North America and has been introduced to the eastern half of the continent and Hawaii. This species and the other two American rosefi ...
es. Flickers excavate larger holes higher on the stem compared to Gila woodpeckers. The resulting nest cavity is deep, and the parents and young are entirely hidden from view. The saguaro creates
callus A callus is an area of thickened and sometimes hardened skin that forms as a response to repeated friction, pressure, or other irritation. Since repeated contact is required, calluses are most often found on the feet and hands, but they may o ...
tissue on the wound. When the saguaro dies and its soft flesh rots, the callus remains as a so-called saguaro boot, which was used by natives for storage. Gila woodpeckers (''Melanerpes uropygialis'') create new nest holes each season rather than reuse the old ones, leaving convenient nest holes for other birds, such as elf owls,
tyrant flycatcher The tyrant flycatchers (Tyrannidae) are a family of passerine birds which occur throughout North and South America. They are considered the largest family of birds known to exist in the world, with more than 400 species. They are the most dive ...
s, and wrens. In recent years, early breeding, aggressive, non-native birds have taken over the nests to the detriment of elf owls that breed and nest later. In 2020, a bald eagle was found nesting in a saguaro for the first time since 1937.


Conservation

Harming or vandalizing a saguaro in any manner, such as shooting them (sometimes known as "cactus plugging") is illegal by state law in Arizona. When houses or highways are built, special permits must be obtained to move or destroy any saguaro affected. Exceptions to this general understanding exist; for example, a private landowner whose property is or less, where the initial construction has already occurred, may remove a saguaro from the property. This is common when the cactus falls over in a storm, its location interferes with a house addition, or it becomes a potential hazard to humans. In 1982, a man was killed after damaging a saguaro. David Grundman was shooting and poking at a saguaro cactus in an effort to make it fall. An arm of the cactus, weighing , fell onto him, crushing him and his car. The trunk of the cactus then also fell on him. The
Austin Lounge Lizards The Austin Lounge Lizards are a musical group from Austin, Texas, formed in 1980. The band includes founding members Hank Card and Conrad Deisler, along with Tim Wilson and Kirk Williams. The third founding member, Tom Pittman, retired from the ...
wrote the song "Saguaro" about this death. Contrary to published statements, no law mandates prison sentences of 25 years for cutting a cactus down; however, it is considered a class-four felony with a possible 3-year, 9-month maximum sentence. Invasive species, such as buffelgrass and Sahara mustard, pose significant threats to the Sonoran Desert ecosystem by increasing the rate of fires. Buffelgrass outcompetes saguaros for water, and grows densely. It is also extremely flammable, but survives fire easily due to deep root systems. Saguaros did not evolve in an environment with frequent fires, thus are not adapted to fire survival. Most Sonoran desert ecosystems have a fire return interval greater than 250 years; buffelgrass thrives at fire return intervals of two to three years. This has led to the reshaping of the Sonoran Desert ecosystem and threatens the survival of the saguaro. Climate change may threaten saguaros and their ecosystems, as deserts are particularly susceptible to climate effects. Rising daytime and nighttime temperatures will reduce the water use efficiency of saguaros, forcing them to use more water and making them more likely to die during drought periods.


Uses


Ethnobotany

The utility of the saguaro is well known to Native Americans such as the
Tohono Oʼodham The Tohono Oʼodham (; Oʼodham: ) are a Native American people of the Sonoran Desert, residing primarily in the U.S. state of Arizona and the northern Mexican state of Sonora. The federally recognized tribe is known in the United States as t ...
, Pima, and
Seri Seri or SERI may refer to: People *Jean Michaël Seri, an Ivorian professional footballer Places *Seri Yek-e Zarruk, Iran *Seri, Bheri, Nepal *Seri, Karnali, Nepal *Seri, Mahakali, Nepal *Seri, Raebareli, a village in Uttar Pradesh, India Oth ...
peoples, who still use nearly every part of the plant. The fruit and seeds are edible, being consumed fresh and dried, and made it into preserves and drinks. The Tohono O'odham use long sticks to harvest the fruits, which are then made into a variety of products including jams, syrups, and wine. The Tohono O'odham begin their harvest in June. A pair of saguaro ribs, about long, is bundled together to make a harvesting tool called a ''kuibit''. The Tohono O'odham traditionally reduce the freshly harvested fruit into a thick syrup through several hours of boiling, as the fresh fruit does not keep for long. of fruit will yield about of syrup. Copious volumes of fruit are harvested; an example harvest in 1929 yielded among 600 families. At the end of the harvest, each family would contribute a small amount of syrup to a communal stock that would be fermented by the medicine man. This was cause for rainmaking celebrations. Stories would be told, there was much dancing, and songs would be sung. Each man would drink some of the saguaro wine. The resulting intoxicated state was seen as holy, and any dreams it brought on were considered portentous. The seeds are ground into meal or eaten raw, but the raw seeds are mostly indigestible. They are also pressed for their oils. They also have minor use in the
tanning Tanning may refer to: *Tanning (leather), treating animal skins to produce leather *Sun tanning, using the sun to darken pale skin **Indoor tanning, the use of artificial light in place of the sun **Sunless tanning, application of a stain or dye t ...
of leather. In modern times, these uses have declined, and the seeds are now mainly used as chicken feed. The ribs of the dead saguaro were used for construction and other purposes by Native Americans. The Tohono O'odham use it for making fences and furniture. The ribs are also used as livestock fodder. A variety of
alkaloid Alkaloids are a class of basic, naturally occurring organic compounds that contain at least one nitrogen atom. This group also includes some related compounds with neutral and even weakly acidic properties. Some synthetic compounds of similar ...
s, including carnegine, gigantine, and salsolidine, make the stems quite bitter, and an unpalatable way to gain water. Reports of saguaro use date back to the
Coronado Coronado may refer to: People * Coronado (surname) * Francisco Vázquez de Coronado (1510–1554), Spanish explorer often referred to simply as "Coronado" * Coronado Chávez (1807–1881), President of Honduras from 1845 to 1847 Places United ...
expeditions of 1540–1542, which noted its use in winemaking. The old bird nests resist the elements and are gathered by Native Americans for use as storage vessels. Cactus boots, excavated by
gilded flicker The gilded flicker (''Colaptes chrysoides'') is a large-sized woodpecker (mean length of ) of the Sonoran, Yuma, and eastern Colorado Desert regions of the southwestern United States and northwestern Mexico, including all of Baja California, ex ...
s and taken from dead saguaros, have been used by native peoples as water containers. The saguaro features prominently in indigenous folklore and religions.


Culture

Arizona made the saguaro blossom its territorial flower on March 13, 1901, and on March 16, 1931, it became the state flower. The saguaro is often used as an emblem in commercials and logos that attempt to convey a sense of the Southwest. Notably, no naturally occurring saguaros are found within of
El Paso, Texas El Paso (; "the pass") is a city in and the county seat, seat of El Paso County, Texas, El Paso County in the western corner of the U.S. state of Texas. The 2020 population of the city from the United States Census Bureau, U.S. Census Bureau w ...
, 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 in the Monument Valley of Arizona, (they only grow naturally in the Sonoran desert of Arizona and Mexico) as well as New Mexico, Utah, and Texas. The
Dallas Dallas () is the List of municipalities in Texas, third largest city in Texas and the largest city in the Dallas–Fort Worth metroplex, the List of metropolitan statistical areas, fourth-largest metropolitan area in the United States at 7.5 ...
, Texas-based band
Reverend Horton Heat The Reverend Horton Heat is the stage name of American musician James C. Heath (born 1959) as well as the name of his Dallas, Texas-based psychobilly trio. Heath is a singer, songwriter and guitarist. A ''Prick'' magazine reviewer called Heath ...
pokes fun at this phenomenon in their song "Ain't no Saguaro in Texas."


Gallery

File:Saguaro Sunset.jpg, Silhouette at sunset File:Saguaro Cactus AZ.jpg, Saguaro towering over a man File:Saguaro5763.jpg, Mature five-armed in flower File:Saguaro-3.jpg, Snow-covered saguaro near Tucson. File:Saguaro1a.jpg, Needles,
Paradise Valley, Arizona Paradise Valley is a town in Maricopa County, Arizona, United States, and a suburb of Phoenix, the state's largest city. It is Arizona's wealthiest municipality. The town is known for its luxury golf courses, shopping, expensive real estate, and ...
File:Saguaroflowers.jpg, Flowers,
Scottsdale, Arizona , settlement_type = City , named_for = Winfield Scott , image_skyline = , image_seal = Seal of Scottsdale (Arizona).svg , image_blank_emblem = City of Scottsdale Script Logo.svg , nick ...
File:Dead saguaro1.jpg, The bare wooden ribs of a dead saguaro File:Grand-daddy, the largest saguaro.jpg, Grand-daddy, the largest saguaro ever recorded, died in the early 1990s File:Saguaro Cactus With Desert Butte In Background At Springtime In AZ.jpg, Saguaro cactus in springtime


References


Further reading

* Benson, L. (1981). ''The Cacti of Arizona''. 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


Flora of North America: ''Carnegiea gigantea''

Jepson Flora Project: ''Carnegiea gigantea''

Calphotos: ''Carnegiea gigantea''

USDA Plants Profile: ''Carnegiea gigantea''

SaguaroCactus.org
{{Authority control Cacti of Mexico Cacti of the United States Flora of the Sonoran Deserts Flora of Arizona Flora of Sonora Flora of the California desert regions Flora of Northwestern Mexico Flora of the Southwestern United States North American desert flora Natural history of the Colorado Desert Least concern flora of North America Least concern flora of the United States Plants used in Native American cuisine Plants used in traditional Native American medicine Desert fruits Edible plants Garden plants of North America Drought-tolerant plants Arizona culture