Saguaro#Conservation

The saguaro is a columnar cactus that grows notable branches, usually referred to as arms. Over 50 arms may grow on one plant, with one specimen having 78 arms.{{cite web |title=Saguaro with 78 arms is named 'Shiva' |url=https://www.kgun9.com/news/local-news/how-did-a-saguaro-get-78-arms |publisher=KGUN 9|date=June 24, 2021 |access-date=March 21, 2022 }} Saguaros grow from {{convert|3-16|m|ft|0|abbr=on}} tall, and up to {{convert|75|cm|in|abbr=on}} in diameter. They are slow growing, and routinely live 150 to 200 years. They are the largest cactus in the United States.{{Cite web |url=https://www.fs.fed.us/database/feis/plants/cactus/cargig/all.html |title=Carnegiea gigantea |last=Pavek |first=Diane S. |year=1993 |website=U.S. Forest Service Fire Effects Information System |publisher=U.S. Department of Agriculture, US Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer) |access-date=October 2, 2019 |archive-url=http://web.archive.org/web/20220801173239/https://www.fs.fed.us/database/feis/plants/cactus/cargig/all.html |archive-date=2022-08-01}}{{Cite web |url=https://www.desertmuseum.org/kids/oz/long-fact-sheets/Saguaro%20Cactus.php |title=Saguaro cactus fact sheet |website=desertmuseum.org |access-date=March 27, 2019}}

File:Saguaro with many arms.jpg

The growth rate of this cactus is strongly dependent on precipitation; saguaros in drier western Arizona grow only half as fast as those in and around Tucson. Saguaros grow slowly from seed, and may be only {{convert|1/4|in|mm|order=flip|abbr=on}} 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.{{cite book |title=A Natural History of the Sonoran Desert |edition=revised and updated |year=2000 |series=Arizona-Sonora Desert Museum |publisher=University of California Press |isbn=978-0520219809 |page=193 |url=https://books.google.com/books?id=Lb5I0tcnYNkC&pg=PA193 |via=Google books }} {{As of|2014|since=y|post=,}} the National Register of Champion Trees listed the largest known living saguaro in the United States in Maricopa County, Arizona, measuring {{convert|13.8|m|ftin|abbr=on}} high with a girth of {{convert|3.1|m|ftin|abbr=on}}; it has an estimated age of 200 years and survived damage in the 2005 Cave Creek Complex Fire.{{cite news |first= Henry |last= Brean |date= September 22, 2019 |title=Tree hunters stalk giants for Arizona's growing list of champions|website=tucson.com |url= https://tucson.com/news/local/tree-hunters-stalk-giants-for-arizona-s-growing-list-of/article_b5b9df68-5c17-5a22-bd07-e19d3b281d43.html |access-date= January 30, 2020}}{{cite news |title= Natural Selections: Searching out the saguaro |last= Muller |first= Seth |date= January 13, 2014 |newspaper=Arizona Daily Sun |url= https://azdailysun.com/outdoors/natural-selections-searching-out-the-saguaro/article_97e06fa8-7cb3-11e3-b2fa-0019bb2963f4.html |via=azdailysun.com |access-date= January 30, 2020}} The tallest saguaro ever measured was an armless specimen found near Cave Creek, Arizona. It was {{convert|78|ft|m|1|abbr=on}} in height before it was toppled in 1986 by a windstorm.{{cite news |title=Windstorm fells 78 foot cactus – tallest in world |newspaper=The Los Angeles Times |place=Los Angeles, CA |url=https://www.latimes.com/archives/la-xpm-1986-08-01-mn-19025-story.html |via=latimes.com |access-date=August 4, 2015}} Saguaros are stem succulents and can hold large amounts of water; when rain is plentiful and the saguaro is fully hydrated, it can weigh between {{convert|3200|and|4800|lb|kg|order=flip|abbr=on}}.{{Failed verification|date=March 2025}}

Saguaros have a very large root network that can extend up to {{convert|30|m|ft|-1|abbr=on}}, and long taproots of up to {{convert|1|m|ftin|abbr=on}} deep.

Saguaros may take between 20 and 50 years to reach a height of {{convert|1|m|ftin|abbr=on}}. Individual stomatal guard cells and medulla cells can live and function for as long as 150 years,{{cite journal |last=MacDougal |first=Daniel T. |date=September–October 1926 |title=Growth and penetrability of century-old cells |journal=The American Naturalist |volume=60 |issue=670 |page=411 |doi=10.1086/280113 |s2cid=84028206 }} possibly the longest living of all cells, except possibly nerve cells in some tortoises.{{Citation needed|date=October 2021}}

As a cactus, it uses crassulacean acid metabolism photosynthesis, which confers high levels of water-use efficiency. This allows the saguaro to transpire only at night, minimizing daytime water loss.{{Cite journal |last1=Bronson |first1=Dustin R. |last2=English |first2=Nathan B. |last3=Dettman |first3=David L. |last4=Williams |first4=David G. |date=August 6, 2011 |title=Seasonal photosynthetic gas exchange and water-use efficiency in a constitutive CAM plant, the giant saguaro cactus (Carnegiea gigantea) |journal=Oecologia |lang=en |volume=167 |issue=3 |pages=861–871|doi=10.1007/s00442-011-2021-1|pmid=21822726|issn=1432-1939|bibcode=2011Oecol.167..861B|s2cid=25829629}}

A saguaro without arms is called a "spear".{{cite book |last=Krieg |first=John C. |year= 2018 |title=Desert Landscape Architecture |publisher=CRC Press |isbn=978-1351456104 |page=466 |url=https://books.google.com/books?id=9XuCDwAAQBAJ&pg=PT466 }}

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 2,743 known crested saguaros documented.{{Cite web |title=Crested saguaros |series=Joe Orman's photo pages |website=joeorman.shutterace.com |url=http://joeorman.shutterace.com/Bizarre/Bizarre_Cristate.html |access-date=February 29, 2020 }} The crest formation, caused by fasciation, creates a seam of abnormal growth along the top or top of the arm of the saguaro.{{Cite web|url=http://www.crestedsaguarosociety.org/crested/crested.php|title=Crested Cactus|website=crestedsaguarosociety.org|access-date=February 29, 2020}}

File:SaguaroRibs.jpg

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 {{cvt|430|kg/m3|lb/cuft}},{{cite web |last1=Natsu |title=How two Seattle-area brothers made dwarf fortress |website=Hacker News |url=https://news.ycombinator.com/item?id=11864776 |access-date=29 April 2024}} 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.{{cite press release |title=Memo on harvesting Saguaro ribs |publisher=Arizona Department of Agriculture |url=https://agriculture.az.gov/sites/default/files/Cactus%20Wood%20Rules%20-%20AZ%20Dept%20of%20Ag.pdf |archive-url=https://web.archive.org/web/20200926150216/https://agriculture.az.gov/sites/default/files/Cactus%20Wood%20Rules%20-%20AZ%20Dept%20of%20Ag.pdf |url-status=dead |archive-date=September 26, 2020 |access-date=November 4, 2019}}

The composition of the ribs is similar to that of hardwoods.{{Rp|326}}

File:Carnegiea gigantea trunk - close up (6989395593).jpg

The spines on a saguaro are extremely sharp and can grow to {{convert|7|cm|in|frac=2|abbr=on}} long, and up to {{convert|1|mm|in|frac=32|abbr=on}} 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. A 2007 study examined the relationship of carbon and oxygen isotope ratios in the tissues of spines of an individual to its climate and photosynthetic history (acanthochronology).{{Cite journal|last1=English|first1=N. B.|last2=Dettman|first2=D. L.|last3=Sandquist|first3=D. R.|last4=Williams|first4=D. G.|year=2007|title=Past climate changes and ecophysiological responses recorded in the isotope ratios of saguaro cactus spines|journal=Oecologia|volume=154|issue=2|pages=247–258|doi=10.1007/s00442-007-0832-x|pmid=17724618|bibcode=2007Oecol.154..247E|s2cid=282478}}

The spines may cause significant injury to animals; one paper reported that a bighorn sheep skull had been penetrated by a saguaro spine after the sheep collided with a saguaro.{{cite journal |last1=Jansen |first1=Brian D. |last2=Krausman |first2=Paul R. |last3=Heffelfinger |first3=James R. |last4=de Vos |first4=James C., Jr. |title=Saguaro spine penetrated bighorn sheep skull |date=March 24, 2005 |journal=The Southwestern Naturalist |volume=50 |issue=4 |pages=513–515 |s2cid=85735736 |issn=0038-4909 |doi=10.1894/0038-4909(2005)050[0513:SSPBSS]2.0.CO;2 }} 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. However, spines that remain embedded may cause inflammatory granuloma.{{cite journal |last1=Lindsey |first1=Douglas |last2=Lindsey |first2=Wally E. |date=July 1, 1988 |title=Cactus spine injuries |journal=The American Journal of Emergency Medicine |lang=en |volume=6 |issue=4 |pages=362–369 |issn=0735-6757 |pmid=3390256 |doi=10.1016/0735-6757(88)90158-1 |url=https://www.ajemjournal.com/article/0735-6757(88)90158-1/abstract }}{{dead link|date=February 2025|bot=medic}}{{cbignore|bot=medic}}

File:Carnegiea gigantea (Saguaro cactus) blossoms.jpg

The white, waxy flowers appear in April through June, opening well after sunset and closing in midafternoon. They continue to produce nectar after sunrise.{{cite journal|last1=Fleming |first1=Theodore H. |last2=Sahley|first2=Catherine T.|last3=Holland|first3=J. Nathaniel|last4=Nason |first4=John D. |last5=Hamrick |first5=J. L. |year=2001 |title=Sonoran desert columnar cacti and the evolution of generalized pollination systems |journal=Ecological Monographs |volume=71 |issue=4 |page=511 |issn=0012-9615 |doi=10.1890/0012-9615(2001)071[0511:SDCCAT]2.0.CO;2 |hdl=1911/21702 |url=https://lib.dr.iastate.edu/cgi/viewcontent.cgi?article=1029&context=bot_pubs|hdl-access=free}} Flowers are self-incompatible, 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 {{nobr|totaled {{gaps|3|482}}}} in a single flower.{{cite journal |author=[author not cited] |date=6 November 1914 |title=[title not cited] |journal=Science |volume=40 |page=680 }}{{full citation|date=August 2024}} 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 bees, bats, and white-winged doves. 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, the black-chinned hummingbird, the broad-billed hummingbird, the hooded oriole, Scott's oriole, the Gila woodpecker, the gilded flicker, the verdin, and the house finch 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): 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.{{cite book|last=Abrol|first=Dharam P. |title=Pollination Biology: Biodiversity Conservation and Agricultural Production|url=https://books.google.com/books?id=clwm8CSIIdIC&pg=PA294|year= 2011|publisher=Springer Science & Business Media|isbn=978-9400719422|page=294}}

Flowers grow {{convert|3.4|-|4.9|in|cm|order=flip|abbr=on}} 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 flowers open per day over a bloom period lasting a month. In Southern Arizona, saguaros begin flowering around May 3 and peak on June 4.{{cite journal |last1=Renzi |first1=Julianna |title=A decade of flowering phenology of the keystone saguaro cactus (Carnegiea gigantea) |journal=American Journal of Botany |year=2019 |volume=106 |issue=2 |pages=199–210 |doi=10.1002/ajb2.1231|pmid=30791093 |doi-access=free }} A decline in bat populations causes more daytime flower openings, which favors other pollinators.{{cite journal|vauthors=Fleming TH, Geiselman C, Kress WJ| title=The evolution of bat pollination: a phylogenetic perspective | journal=Annals of Botany | year= 2009 | volume= 104 | issue= 6 | pages= 1017–1043 | pmid=19789175 | doi=10.1093/aob/mcp197 |doi-access=free | pmc=2766192}}

File:Saguaro cactus fruits with bird.jpg perched atop fruits at the tip of a saguaro]]

The ruby red fruits are {{convert|6|to|9|cm|in|frac=2|abbr=on}} long and ripen in June, each containing around {{nobr|{{gaps|2|000}} seeds,}} plus sweet, fleshy connective tissue.{{cite book |last=Nabhan |first=Gary Paul |year=2004 |title=Conserving Migratory Pollinators and Nectar Corridors in Western North America |publisher=University of Arizona Press |isbn=978-0816522545 |page=124 |url=https://books.google.com/books?id=jW0t__Ls-FUC&pg=PA124 }}

The fruits are often out of reach and are harvested using a pole (made of two or three saguaro ribs) {{convert|4.5|to|9|m|ft|0|abbr=on}} long, to the end of which cross-pieces, which can be made of saguaro rib, catclaw, or creosote bush, are attached. This pole is used to hook the fruits or knock them free.{{cite report |title=Saguaro fruit: A traditional harvest |website=nps.gov |publisher=U.S. National Park Service |url=https://www.nps.gov/sagu/learn/historyculture/upload/Saguaro-Fruit-A-Traditional-Harvest-Brief.pdf |archive-url=https://web.archive.org/web/20170217093544/https://www.nps.gov/sagu/learn/historyculture/upload/Saguaro-Fruit-A-Traditional-Harvest-Brief.pdf |url-status=dead |archive-date=February 17, 2017 |access-date=December 21, 2019}}

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 12–14 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, among others. While nurse plants reduce summer temperature maxima by as much as {{convert|18|C-change|F-change|abbr=on}}, they are more important in raising winter minimum temperatures, as extended frosts limit the range of saguaros.{{cite journal |last1=Drezner |first1=Taly D. |last2=Garrity |first2=Colleen M. |date=November 1, 2003 |title=Saguaro distribution under nurse plants in Arizona's Sonoran desert: Directional and microclimate influences |journal=The Professional Geographer |volume=55 |issue=4 |pages=505–512 |doi=10.1111/0033-0124.5504008 |bibcode=2003ProfG..55..505D |s2cid=128958283 |issn=0033-0124}}

Native American Indians of the Southwest would make bread from the ground seeds of saguaro.{{cite book |last=Niethammer |first=Carolyn |year=1974 |title=American Indian Food and Lore |publisher=Simon & Schuster / Macmillan Company |location=New York, NY |isbn=0-02-010000-0 |page=27 }}

The saguaro genome is around 1 billion base pairs long.{{cite web |title=Assembly |department=Genome |publisher=NCBI |id=SGP5 Cgig |edition=v 1.3 |website=ncbi.nlm.nih.gov |url=https://www.ncbi.nlm.nih.gov/assembly/GCA_002740515.1/ |access-date=April 24, 2018}} 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, the saguaro has lost the ndh plastid genes, which codes for production of NADPH dehydrogenase pathway, but unlike those taxa, the saguaro remains fully autotrophic; 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 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.{{cite journal |last1=Sanderson |first1=Michael J. |last2=Copetti |first2=Dario |last3=Búrquez |first3=Alberto |last4=Bustamante |first4=Enriquena |last5=Charboneau |first5=Joseph L.M. |last6=Eguiarte |first6=Luis E. |last7=Kumar |first7=Sudhir |last8=Lee|first8=Hyun Oh |last9=Lee |first9=Junki |display-authors=6 |date=July 1, 2015 |title=Exceptional reduction of the plastid genome of saguaro cactus (Carnegiea gigantea): Loss of the ndh gene suite and inverted repeat |journal=American Journal of Botany |lang=en |volume=102 |issue=7 |pages=1115–1127 |doi=10.3732/ajb.1500184 |doi-access=free |issn=0002-9122 |pmid=26199368 |hdl=2286/R.I.35789 |hdl-access=free}}

Carnegiea gigantea is the only species in the monotypic genus Carnegiea. The first description of the species was made by William H. Emory in 1848, during his surveys along the pre-Gadsden Purchase United States-Mexican border.{{cite book|title=The Expeditions of John Charles Fremont, vol 3, Travels from 1848 to 1854|last1=Spence|first1=Mary Lee|date=1984|publisher=University of Illinois Press|isbn=978-0252004162|location=Urbana, Illinois|pages=495–496}} This description allowed cactus expert George Engelmann to formally name it, during his work on the United States and Mexican Boundary Survey, published in 1859.{{Cite web|url=https://www.lindahall.org/george-engelmann/|title=George Engelmann – Scientist of the Day|date=February 2, 2017|website=Linda Hall Library|language=en-US|access-date=November 4, 2019}} The next major taxonomic treatment came from The Cactaceae, the seminal work on cactus by Nathaniel Lord Britton and Joseph Nelson Rose.{{Citation needed|date=April 2020}}

What tribe 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.{{Cite journal|last1=Nyffeler|first1=R.|last2=Eggli|first2=U.|year=2010|title=A farewell to dated ideas and concepts: molecular phylogenetics and a revised suprageneric classification of the family Cactaceae|url=http://www.kakteen.org/schumannia.shtml|journal=Schumannia|volume=6|pages=109–149|doi=10.5167/uzh-43285|s2cid=89650660|issn=1437-2517|access-date=November 4, 2019|archive-date=July 15, 2016|archive-url=https://web.archive.org/web/20160715195341/http://kakteen.org/schumannia.shtml|url-status=dead}} The ARS Germplasm Resources Information Network places it in the Echinocereeae.{{Cite web|url=https://npgsweb.ars-grin.gov/gringlobal/taxonomydetail.aspx?id=310457|title=Taxonomy – GRIN-Global Web v 1.10.5.0|website=npgsweb.ars-grin.gov|access-date=November 4, 2019}}

The generic name honors businessman and philanthropist Andrew Carnegie.{{Cite web|url=https://www.azcentral.com/story/news/local/arizona/2016/08/04/8-things-you-might-not-know-about-the-saguaro-cactus/87461022/|title=Saguaro cactus: 8 things you might not know|last=Schlosser|first=S. E.|website=The Arizona Republic|language=en|access-date=December 17, 2019}} The specific epithet gigantea refers to its formidable size.{{Cite book|url=https://www.nps.gov/sagu/learn/nature/upload/Common-Plants-of-Saguaro-NP.pdf|archive-url=https://web.archive.org/web/20170211155754/https://www.nps.gov/sagu/learn/nature/upload/Common-Plants-of-Saguaro-NP.pdf|url-status=dead|archive-date=February 11, 2017|title=Common Plants of Saguaro National Park|last=Buckley|first=Steve|publisher=National Park Service; Sonoran Desert Network|year=2011|page=63|orig-year=First published 2009}}

File:Sahuaros en Ímuris.jpg, Sonora.]]

The Saguaro is endemic to the Sonoran Desert and is found primarily in western Sonora in Mexico, and in western Arizona in the US. There are only 30 known wild saguaros found in southeastern California.{{Cite web|url=https://wildlife.ca.gov/Data/CNDDB/News/taxon-of-the-week-the-saguaro-cactus|title=CNDDB News | Taxon of the Week: The Saguaro Cactus|website=wildlife.ca.gov}} 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, New Mexico, Texas, Colorado, Utah, nor in the high deserts of northern Arizona.{{cite web |title=Where saguaros grow |url=http://www.nps.gov/sagu/learn/nature/location.htm |archive-url=https://web.archive.org/web/20150901231722/http://www.nps.gov/sagu/learn/nature/location.htm |url-status=dead |archive-date=September 1, 2015 |access-date=April 24, 2018 |series=Saguaro National Park |publisher=U.S. National Park Service |via=nps.gov/sagu}} The northern limits of their range are the Hualapai Mountains in Arizona. They are the northernmost columnar cacti in the Americas.{{Cite journal|last=Bruhn|first=Jan G.|year=1971|title=Carnegiea gigantea: The Saguaro and Its Uses|journal=Economic Botany|volume=25|issue=3|pages=320–329|issn=0013-0001|jstor=4253267|doi=10.1007/BF02860768|bibcode=1971EcBot..25..320B |s2cid=44788245}}{{Rp|320}} The range of the saguaro is strongly correlated with low minimum temperature stress and low minimum VPD.{{cite journal |date=2024-10-18 |first1=Narayani |last1=Barve |first2=Uzma |last2=Ashraf |first3=Vijay |last3=Barve |first4=Marlon E. |last4=Cobos |first5=Claudia |last5=Nuñez-Penichet |first6=Andrew |last6=Townsend Peterson |title=Revisiting plant hardiness zones to include multiple climatic stress dimensions |page=110824 |doi=10.1016/j.isci.2024.110824 |journal=iScience |eissn=2589-0042 |volume=27 |issue=10|pmid=39435139 |bibcode=2024iSci...27k0824B |pmc=11491728 }}

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.{{Cite journal|last=Drezner|first=Taly Dawn|date=June 1, 2014|title=The keystone saguaro (Carnegiea gigantea, Cactaceae): a review of its ecology, associations, reproduction, limits, and demographics|journal=Plant Ecology|language=en|volume=215|issue=6|pages=581–595|doi=10.1007/s11258-014-0326-y|bibcode=2014PlEco.215..581D |s2cid=18807470|issn=1573-5052}}

The saguaro provides voluminous amounts of pollen, nectar, and fruits. The fruits are eaten by the white-winged dove and ants, so that seeds rarely escape to germinate.{{cite book|last=Peattie|first=Donald Culross|title=A Natural History of Western Trees|publisher=Bonanza Books|year=1953|location=New York|pages=647, 649|author-link=Donald C. Peattie}} 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.{{Cite web|url=https://permanent.fdlp.gov/FDLP1608/DoveandPigeonStatusReport2009.pdf|title=Mourning Dove, White-winged Dove, and Band-tailed Pigeon: 2009 population status|last=Rabe|first=Michael J.|date=June 2009|editor-last=Sanders|editor-first=Todd A.|publisher=United States Fish and Wildlife Service|location=Laurel, Maryland|pages=25–32}} {{PD-notice}}

Gila woodpeckers and gilded flickers create holes in the cactus to make nests, which are later used by other birds, such as elf owls, purple martins, and house finches.{{efn|name=NatCons-GilaWdpkr-quote}}

{{cite book

|last1=Elbroch |first1=Mark

|last2=Marks |first2=Eleanor Marie

|last3=Boretos |first3=C. Diane

|year= 2001

|title= Bird Tracks and Sign

|publisher= Stackpole Books

|page= 311

|url=https://books.google.com/books?id=1avqcmYRwrcC |via=Google books

|isbn=0811726967

}}

{{efn|

Cavities in saguaro cactuses in the Southwest are common. Both gilded flickers and Gila woodpeckers make these cavities for nesting, but they often choose different locations on the cactus. The stouter bills of the gilded flickers allow them to cut cavities through the wooden ribs near the top of the cactus where the ribs converge.

:

Gila woodpeckers stay at midlevel on the cactus where the ribs are separated enough to cut a cavity between them. Cavities in saguaros are cut out by these birds the year before they are inhabited. The excavated cactus secretes a fluid that hardens into a scab, thus preventing water loss, which could kill the cactus, as well as waterproofing the inside of the nest cavity. — {{harvp|Elbroch|Marks|Boretos|2001|p=311}}

}}{{Cite web |title=Gila woodpecker fact sheet |website=desertmuseum.org |url=https://www.desertmuseum.org/kids/oz/long-fact-sheets/Gila%20Woodpecker.php |access-date=February 22, 2019}} Gilded 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 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 flycatchers, and wrens.{{efn

|name=NatCons-GilaWdpkr-quote|

Although they do not use them immediately, waiting first for the sap to harden, Gila woodpeckers excavate cavities in cacti and trees as nesting sites. Females typically lay two broods a year of three to five eggs, which incubate for 14 days.

:

Once abandoned, the cavities are occupied by reptiles, rodents, and small birds like kestrels, elf owls, flycatchers, and wrens.

:

In the desert, the woodpeckers perform the important ecological function of removing unhealthy flesh from the saguaro cactus. Some insects on which it feeds carry diseases, harmless to the bird, which damages the cactus and leaves discolorations. The marks signal larvae to the bird, and as it excavates the insects, it also cuts away the diseased tissue. As the sap hardens, the cactus is healed, and the excavation becomes a convenient nesting site. — Nature Conservancy

}}

{{cite web

|title=Gila woodpecker

|department=Special features

|series=Birds

|publisher=Nature Conservancy

|url=http://www.nature.org/newsfeatures/specialfeatures/animals/birds/gila-woodpecker.xml

|url-status=dead |via=nature.org |access-date=October 28, 2011

|archive-url=https://web.archive.org/web/20161215025321/http://www.nature.org/newsfeatures/specialfeatures/animals/birds/gila-woodpecker.xml

|archive-date=December 15, 2016

}}

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.{{Citation needed|date=October 2019}} In 2020, a bald eagle was found nesting in a saguaro for the first time since 1937.

{{cite news

|title=AZGFD spots first documented bald eagle nest in saguaro

|date=April 16, 2020

|publisher=KGUN-TV |place=Tucson, AZ

|url=https://www.kgun9.com/news/local-news/azgfd-spots-first-documented-bald-eagle-nest-in-saguaro

|access-date=April 16, 2020

|lang=en

}}

{{cite news

|title=Bald eagles, eaglets found nesting in arms of Arizona cactus

|date=April 16, 2020

|agency=Associated Press

|newspaper=The New York Times

|issn=0362-4331

|url=https://www.nytimes.com/aponline/2020/04/16/us/ap-us-cactus-eagles-nest.html

|access-date=April 16, 2020

|lang=en-US }}

Saguaros transform significant amounts of the carbon in carbon dioxide into the mineral calcium carbonate when they die. Through the formation of a mineral, cacti transfer carbon from the earth's biological cycle to its geological cycle. This form of carbon sequestration is a terrestrial equivalent to oceanic sequestration by corals and shellfish.{{Cite web |date=2021-10-18 |title=Carbon Sequestration and Sonoran Desert Cacti |url=https://blog.azgs.arizona.edu/index.php/blog/2021-10/carbon-sequestration-and-sonoran-desert-cacti |access-date=2024-09-21 |website=e-Magazine of the AZ Geological Survey}}{{Cite journal |last=Garvie |first=Laurence A. J. |date=2006 |title=Decay of cacti and carbon cycling |url=https://pubmed.ncbi.nlm.nih.gov/16453105/ |journal=Die Naturwissenschaften |volume=93 |issue=3 |pages=114–118 |doi=10.1007/s00114-005-0069-7 |issn=0028-1042 |pmid=16453105|bibcode=2006NW.....93..114G }}

File:A large cactus (Carnegiea gigantea) at Saguaro National Park.jpg|alt={{ Convert | 6 | ft || adj=on }} man standing next to a large Saguaro at Saguaro National Park]]

File:Saguro Cactus Impact (1060).jpg

Harming or vandalizing a saguaro in any manner, such as shooting them (sometimes known as "cactus plugging"){{Citation|last1=Klingaman |first1=Gerald |title=Plant of the Week: Saguaro Cactus |publisher=University of Arkansas |date=December 12, 2008 |url=http://www.arhomeandgarden.org/plantoftheweek/articles/saguaro_cactus_12-12-08.htm |access-date=February 13, 2013 |postscript=. |url-status=dead |archive-url=https://web.archive.org/web/20130405230825/http://www.arhomeandgarden.org/plantoftheweek/articles/saguaro_cactus_12-12-08.htm |archive-date=April 5, 2013 }} 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.{{cite web|url=http://www.azda.gov/esd/NpRulesHome.aspx |title=Article 11: Arizona Native Plants |work=Arizona Department of Agriculture |url-status=dead |archive-url=https://web.archive.org/web/20130920183147/http://www.azda.gov/esd/NpRulesHome.aspx |archive-date=September 20, 2013 }} Exceptions to this general understanding exist; for example, a private landowner whose property is {{convert|10|acre|ha|0|abbr=off}} or less, where the initial construction has already occurred, may remove a saguaro from the property.{{cite web|url=http://www.azda.gov/ESD/ESD571a.pdf |publisher=Arizona Department of Agriculture |title=Private Landowners Clearing Protected Native Plants |url-status=dead

|archive-url=https://web.archive.org/web/20130920175927/http://www.azda.gov/esd/ESD571a.pdf |archive-date=September 20, 2013 }} 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.{{cite web|url=http://www.azleg.gov/FormatDocument.asp?inDoc=/ars/3/00904.htm&Title=3&DocType=ARS|title=Arizona Revised Statutes, A.R.S. 3-904.(H): Destruction of protected plants by private landowners; notice; exception|publisher=Arizona State Legislature|access-date=December 18, 2021|archive-date=October 16, 2018|archive-url=https://web.archive.org/web/20181016165446/https://www.azleg.gov/FormatDocument.asp?inDoc=%2Fars%2F3%2F00904.htm&Title=3&DocType=ARS|url-status=dead}}

{{anchor|David Grundman}}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 {{convert|500|lb|kg|order=flip|abbr=on}}, fell onto him, crushing him and his car. The trunk of the cactus then also fell on him.{{Citation|last=Mikkelson |first=David |title=Death by Saguaro| publisher=Snopes |date=February 8, 2015 |url=http://www.snopes.com/horrors/freakish/saguaro.asp |access-date=January 20, 2017}} The Austin Lounge Lizards wrote the song "Saguaro" about this death.

Contrary to published statements,{{cite web |url=http://www.tucsonnewsnow.com/story/20189233/only-on-kold-stange-laws-still-on-the-books-in-arizona |title=Only On Hold Strange Laws Still On The Books In Arizona |last=Trimble|first=Marshall |year=2012 |website=Tucson News Now |publisher=Hold |access-date=July 2, 2017}} 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.{{cite web |url=http://cronkitezine.asu.edu/spring2010/arizonalaws/nativeplants.html |title=Safety of native plants protected under Arizona law |last=Snyder |first=Stephanie |year=2010 |website=ASU.edu |publisher=Chevas Samuels, McKenzie Manning, Stephanie Snyder |access-date=July 2, 2017 |quote="While damaging a cactus in Arizona will not warrant the rumored possibility of 25 years in prison, it is still considered a class four felony." |archive-date=October 14, 2018 |archive-url=https://web.archive.org/web/20181014150006/http://cronkitezine.asu.edu/spring2010/arizonalaws/nativeplants.html |url-status=dead }}

Invasive species, such as buffelgrass and Sahara mustard, pose significant threats to the Sonoran Desert ecosystem by increasing the rate of fires.{{Cite journal|last=Schiermeier|first=Quirin|date=June 1, 2005|title=Pall hangs over desert's future as alien weeds fuel wildfires|journal=Nature|language=en|volume=435|issue=7043|page=724|doi=10.1038/435724b|pmid=15944662|issn=1476-4687|bibcode=2005Natur.435..724S|s2cid=1678763|doi-access=free}} Buffelgrass outcompetes saguaros for water, and grows densely. It is also extremely flammable, but survives fire easily due to deep root systems.{{Cite journal|last1=Marshall|first1=V. M.|last2=Lewis|first2=M. M.|last3=Ostendorf|first3=B.|date=March 1, 2012|title=Buffel grass (Cenchrus ciliaris) as an invader and threat to biodiversity in arid environments: A review|journal=Journal of Arid Environments|volume=78|pages=1–12|doi=10.1016/j.jaridenv.2011.11.005|issn=0140-1963|bibcode=2012JArEn..78....1M|doi-access=free}} 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.{{Cite web|url=https://www.fs.fed.us/database/feis/plants/graminoid/pencil/all.html|title=Pennisetum ciliare|last=Hauser|first=A. Scott|year=1993|website=US Forest Service Fire Effects Information System|publisher=U.S. Department of Agriculture, US Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer)|access-date=October 2, 2019}}

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.

File:Saguaro gatherers2.jpg women gathering saguaro fruits, photo by Edward S. Curtis, 1907]]

The utility of the saguaro is well known to Native Americans such as the Tohono O'odham, Pima, and Seri peoples, who still use nearly every part of the plant.{{cite book |editor1-first=Steven J. |editor1-last=Phillips |editor2-first=Patricia |editor2-last=Comus |year=2000 |title=A Natural History of the Sonoran Desert |publisher=University of California Press |place=Berkeley, CA |page=193 }} The fruit and seeds are edible, being consumed fresh and dried, and made into preserves and drinks.{{cite book |last=Little |first=Elbert L. |year=1994 |orig-year=1980 |title=The Audubon Society Field Guide to North American Trees |volume=Western Region |publisher=Knopf / Chanticleer Press |isbn=0394507614 |page=562 }} 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 {{convert|20|ft|m|0|abbr=on|order=flip}} long, are 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. {{convert|4|kg|lb|0|abbr=off|spell=In}} of fruit will yield about {{convert|1|L|USgal|frac=4|abbr=off|sp=us}} of syrup. Copious volumes of fruit are harvested; an example harvest in 1929 yielded {{convert|45000|kg|lb|abbr=on}} among 600 families.{{rp|324–326}} 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.{{Cite book |last=Greene |first=Jacqueline Dembar |year=1998 |title=The Tohono O'odham |publisher=Franklin Watts |location=New York, NY |isbn=0531203263 |oclc=36713087 |url=https://www.worldcat.org/oclc/36713087 }}{{Rp|17–20}}

• 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 of leather. In modern times, these uses have declined, and the seeds are now mainly used as chicken feed.{{rp|324}}

• 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 alkaloids, including carnegine, gigantine, and salsolidine, make the stems quite bitter, and an unpalatable way to gain water.{{rp|323}}

• The old bird nests resist the elements and are gathered by Native Americans for use as storage vessels. Cactus boots, excavated by birds and taken from dead saguaros have been used by native peoples as water containers.

The saguaro features prominently in indigenous folklore and religions.{{rp|320}}

Reports of saguaro use date back to the Coronado expeditions of 1540–1542, which noted its use in winemaking.{{rp|324}}

Arizona made the saguaro blossom its territorial flower on March 13, 1901, and on March 16, 1931, it became the state flower.{{cite book |last=Brewer |first=Janice K. |author-link=Jan Brewer |url=https://azmemory.azlibrary.gov/digital/collection/statepubs/id/30409 |title=Arizona Blue Book |date=2003–2004 |access-date=31 January 2020 |via=azmemory.azlibrary.gov}}

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 {{convert|250|mi|km|abbr=off|sp=us|order=flip}} of El Paso, Texas, but the silhouette is found on the label of Old El Paso brand products.{{cite web |title=Cooking ideas from old El Paso |url=http://www.oldelpaso.com/ |access-date=April 24, 2018 |website=oldelpaso.com |publisher=General Mills}}{{cite web |title=Where saguaros grow |url=http://www.nps.gov/sagu/learn/nature/location.htm |archive-url=https://web.archive.org/web/20150901231722/http://www.nps.gov/sagu/learn/nature/location.htm |url-status=dead |archive-date=September 1, 2015 |access-date=April 24, 2018 |series=Saguaro National Park |publisher=U.S. National Park Service |via=nps.gov/sagu}} Though the geographic anomaly has lessened in recent years,{{cn|date=August 2023}} Western films once enthusiastically placed saguaros in the Monument Valley of Arizona (north of their native range), as well as New Mexico, Utah, and Texas.

America West Airlines, and later U.S. Airways after their merger in 2007, used the call sign "CACTUS" for radio communication on flights. America West was based in Phoenix, AZ, and "cactus" was chosen as a tribute to the saguaro cacti growing in the Phoenix area.{{Citation needed|date=October 2024}}

File:Saguaro Sunset.jpg|File:Crestedsaguaro.jpgSilhouette at sunset

File:Saguaro Cactus AZ.jpg|Saguaro towering over a {{convert|6|ft|m|1|abbr=on}} 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

File:Saguaroflowers.jpg|Flowers, Scottsdale, Arizona

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 in blossom in springtime

{{notelist}}

{{reflist|25em}}

{{refbegin|25em|small=yes}}

• {{cite book

|last=Benson |first=L.

|year=1981

|title=The Cacti of Arizona

|publisher=University of Arizona Press |place=Tucson, AZ

|isbn=0816505098

}}

• {{cite journal

|last=Drezner |first=T.D.

|year=2005

|title=Saguaro (Carnegiea gigantea, Cactaceae) growth rate over its American range and the link to summer precipitation

|journal=The Southwestern Naturalist

|volume=50 |pages=65–68

|doi=10.1894/0038-4909(2005)050<0065:SCGCGR>2.0.CO;2

}}

• {{cite book

|last1=Felger |first1=Richard

|last2=Moser |first2=Mary B.

|year=1985

|title=People of the Desert and Sea: Ethnobotany of the Seri Indians

|location=Tucson, AZ |publisher=University of Arizona Press

|isbn=978-0816508181

|url=https://archive.org/details/peopleofdesertse0000felg

|via=Internet Archive |url-access=registration

}}

{{refend}}

{{Sister project links|wikt=saguaro|commons=Carnegiea|b=no|n=no|q=no|s=no|v=no|voy=no|species=Carnegiea|d=no}}

• [http://www.efloras.org/florataxon.aspx?flora_id=1&taxon_id=242412565 Flora of North America: Carnegiea gigantea]
• [http://ucjeps.berkeley.edu/cgi-bin/get_JM_treatment.pl?2702,2705,2706 Jepson Flora Project: Carnegiea gigantea]
• [http://calphotos.berkeley.edu/cgi/img_query?query_src=ucjeps&where-genre=Plant&where-taxon=Carnegiea+gigantea Calphotos: Carnegiea gigantea]
• [http://plants.usda.gov/java/profile?symbol=CAGI10 USDA Plants Profile: Carnegiea gigantea]
• [http://www.saguarocactus.org SaguaroCactus.org]

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{{US state flowers}}

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Category:Cacti of Mexico

Category:Cacti of the United States

Category:Flora of the Sonoran Deserts

Category:Flora of Arizona

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Category:Flora of the California desert regions

Category:Flora of Northwestern Mexico

Category:Flora of the Southwestern United States

Category:North American desert flora

Category:Natural history of the Colorado Desert

Category:Least concern flora of North America

Category:Least concern flora of the United States

Category:Plants used in Native American cuisine

Category:Plants used in traditional Native American medicine

Category:Desert fruits

Category:Edible plants

Category:Garden plants of North America

Category:Drought-tolerant plants

Category:Arizona culture

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