{{Taxobox
| name = Saguaro
| image = Saguaro cactus in Arizona.jpg 
| image_width = 300px
| regnum = Plantae
| divisio = Magnoliophyta
| classis = Magnoliopsida
| ordo = Caryophyllales
| familia = Cactaceae
| subfamilia = Cactoideae
| tribus = Pachycereeae
| genus = '''''Carnegiea'''''
| genus_authority = Britton & Rose
| species = '''''C. gigantea'''''
| binomial = ''Carnegiea gigantea''
| binomial_authority = Britton & Rose
| synonyms = ''Cereus giganteus'' <small>Engelm.</small>
}}

The '''Saguaro''', pronounced "sah-wah-roh", (''Carnegiea gigantea'') is a large, tree-sized Mexican states of state flower of Arizona.

The common name of the cactus, ''saguaro'', is a Spanish-language adaptation of a word used by a local aboriginal American nation, the Tohono O'odham, for the plant. Local English speakers pronounce it .

Saguaros have a relatively long life span.  They take up to 75&nbsp;years to develop a side arm. The arms themselves are grown to increase the plants reproductive capacity (more apices equal more flowers and fruit). The growth rate of saguaros is strongly dependent on local precipitation patterns, and saguaros in drier western Arizona grow only half as fast as those in and around Tucson, Arizona (Drezner, 2003). Some specimens may live for more than 150&nbsp;years;<ref></ref> the champion saguaro grows in Maricopa County, Arizona and is  tall with a girth of .  (It was injured as a result of the Cave Creek Complex fire in June 2005.) In addition to being slow growing, they are also slow to propagate. Harming one 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 spines on smaller saguaro (having a height less than 2&nbsp;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 (one light/dark couplet equals one day of 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.<ref>English NB, Dettman DL, Sandquist DR and DG Williams (2007) Annual and sub-annual variations of δ18O, δ13C and F<sup>14</sup>C in the spines of a columnar cactus, Carnegiea gigantea. Oecologia 154:247-258. DOI 10.1007/s00442-007-0832-x</ref>

The night blooming flowers appear April-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 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. The characteristics of the flower are geared toward pollination by the bats:  the nocturnal opening of the flowers, maturation of pollen, and the nectar. <!-- Position high above the ground, heavy texture, fragrance emitted at night. The amino acids in the pollen. Against this idea are the flowers remain open into the next day and produce more nectar after sunrise. However comparatively Bees and Doves will actually pollinate more gross flowers, this is due to the larger populations. COMMENTED OUT UNTIL IT CAN BE TURNED INTO PARAGRAPH STYLE -->
 
Gila Woodpecker, Purple Martins, House Finches, and Gilded Flicker live in holes inside saguaros. Flickers excavate larger holes higher on the stem, penetrating the ribs. Their holes sometimes cause enough damage to cause death and other problems. These woodpeckers create new nest holes each season, rather than reuse the old ones, thus leaving convenient nest holes for a variety of other animals, especially birds such as the Elf Owl. 

thumb|left|upright|Some saguaro are "crested" due to [[fasciation, instead of having arms]]
The ribs of the saguaro were used for construction and other purposes by aboriginal Americans of the region. 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 a generic 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&nbsp;miles (400&nbsp;km) of El Paso, Texas, even though the silhouette is found on the label of Old El Paso brand products.  There are also no wild saguaros anywhere in such western U.S. states as Texas, Colorado, Utah, New Mexico, or Nevada. The "Peoria Saguaros" are a minor league baseball team that participates in the Arizona Fall League every year.

<!-- Für Informationen zum Umgang mit dieser Tabelle siehe bitte Wikipedia:Taxoboxen. -->
{{Taxobox
| Taxon_WissName   = Carnegiea gigantea
| Taxon_Rang       = Art
| Taxon_Autor      = (Engelm.) Britton & Rose
| Taxon2_WissName  = Carnegiea
| Taxon2_LinkName  = nein
| Taxon2_Rang      = Gattung
| Taxon3_WissName  = Pachycereeae
| Taxon3_Rang      = Tribus
| Taxon4_Name      = Eigentliche Kakteen
| Taxon4_WissName  = Cactoideae
| Taxon4_Rang      = Unterfamilie
| Taxon5_Name      = Kakteengewächse
| Taxon5_WissName  = Cactaceae
| Taxon5_Rang      = Familie
| Taxon6_Name      = Nelkenartige
| Taxon6_WissName  = Caryophyllales
| Taxon6_Rang      = Ordnung
| Bild             = Saguaro1.JPG
| Bildbeschreibung = ''Carnegiea gigantea''
}}

thumb|200px|Bestand von ''Carnegiea gigantea'' in [[Arizona]]
thumb|200px|Dornen
thumb|200px|Blüten
thumb|200px|Unreife Früchte
thumb|200px|Jungpflanze, ca. 85&nbsp;mm, 3-4 Jahre alt
'''''Carnegiea gigantea''''', auch '''Saguaro''' bzw. '''Sahuaro''' genannt, ist die einzige Pflanzenart der Familie der botanische Name wurde ihr zu Ehren des US-amerikanischen Industriellen und Philanthropen Andrew Carnegie gegeben.

== Beschreibung ==
Die Pflanzen sind sehr große, säulenförmige Stammsukkulenten mit einem sehr flachen Wurzelsystem und wenigen, erst in hohem Alter gebildeten Zweigen. Die Hauptsprosse werden etwa 12 bis 15 m (teilweise auch bis zu 20 m) groß und 30 bis 70 cm dick. Die in mehreren Metern Höhe stehenden Zweige sind aufrecht gehalten. Die auf den zwölf bis 24 gerundeten Rippen stehenden, braunen Randdornen und drei bis sechs kräftige, bis 7 cm lange Mitteldornen. In der Höhe der Pflanze werden die grauen Dornen kürzer und feiner.

Die von den scheitelnahen Areolen gebildeten Blütenhüllblätter sind weiß bis cremefarben. Die nach Früchte sind 6 bis 9 cm lang, außen schwach befilzt und tragen auf den Areolen manchmal ein bis drei dünne Dornen. Bei Reife werden die Früchte innen und außen rot und klappen von der Spitze her auf. Die sehr vielen (bis 4000), etwa 2 mm großen Samen sind schwarz.

== Verbreitung ==
''Carnegia gigantea'' ist an den Rändern der Sonora und Touristen besuchten Pflanzen stehen im Saguaro-Nationalpark.

== Ökologie ==
Die Blütezeit an den Standorten der Pflanzen ist Mai bis Juni, kurz vor Beginn der Taube ''Zenaida asiatica'', die Beutelmeise ''Karmingimpel ''Carpodacus mexicanus''.<ref>Theodore H. Fleming: ''Sonoran desert columnar cacti and the evolution of generalized pollination systems'', Ecological Monographs 71(4): 511-530, 2001</ref>.

Die schon als Bestäuber erwähnten  Spechte bauen in einigen Metern Höhe ihre Bruthöhlen in die Stämme. Die großen Kakteen dienen auch Greifvögeln wie Falken als Ansitze zur Jagd und in Ermangelung von Bäumen als einzige Gelegenheit, geschützte Horste zu bauen.

Das Verbreitungsgebiet von ''Carnegiea gigantea'' ist einerseits von zu großer Trockenheit, andererseits von Buschbränden und Blitzschlägen. Ihre dicht unter der Erdoberfläche verlaufende Wurzeln, mit denen sie auch kleinste Niederschlagsmengen schnell aufnehmen können, machen sie anfällig für Windbruch.