The Saguaro Cactus

1 The Saguaro CactusWhere do saguarosgrow? Saguaro cacti, Carnegiea gigantea, onlygrow in the Sonoran Desert. However,they do not grow in all parts of theSonoran Desert. The map at left re p -resents the range of the SonoranDesert (crosshatch) with an overlay ofthe range of the Saguaro Cactus (solid).The range of the Saguaro is limited byfreezing temperatures in do saguarosgrow?Saguaros are a very slow growingcactus. In Saguaro National Park,studies indicate that a Saguaro growsbetween 1 and inches in the firsteight years of its tiny, young saguaros are veryhard to find as they grow under theprotection of a nurse tree , mostoften a palo verde, ironwood or mes-quite tree. As the Saguaro continues togrow, its much older nurse tree maydie. Some scientists believe that com-petition from the Saguaro may lead tothe death of the nurse tree by takingwater and nutrients from the soil in theimmediate a Saguaro begins to age, growthrates vary depending on climate,precipitation and location.

2 We doknow that the period of greatestgrowth in a Saguaro Cactus is fromunbranched to branched at Saguaro National Park,branches normally begin to appearwhen a Saguaro reaches 50 to 70 yearsof age. In areas of lower precipitation, itmay take up to 100 years before a Saguaro reaches 35 years of ageit begins to produce flowers. Thoughnormally found at the terminal end ofthe main trunk and arms, flowers mayalso occur down the sides of the will continue to be producedthroughout a Saguaro s adult Saguaro is generally consid-ered to be about 125 years of age. It mayweigh 6 tons or more and be as tall as50 feet. The average life span of asaguaro is probably 150 - 175 years ofage. However, biologists believe thatsome plants may live over 200 are saguarospleated?The roots of a Saguaro grow out fromthe plant in a radial fashion, severalinches under the ground.

3 During aheavy rain, a Saguaro will absorb asmuch water as its root system accomodate this potentially largeinflux of water, the pleats expand likean accordion. Conversely, when thedesert is dry, the Saguaro uses itsstored water and the pleats are also limited by are generally found growing fromsea level to approximately 4,000 feet inelevation. Saguaros growing higherthan 4,000 feet are usually found onsouth facing slopes where freezingtemperatures are less likely to occur orare shorter in the majority of a Saguaro ismade up of water, an adult plant mayweigh 6 tons or more. This tremendousweight is supported by a circular skel -eton of inter-connected, woody number of ribs inside the plantcorrespond to the number of pleats onthe outside of the plant. As the saguarogrows, the ribs will occasionally forkand the corresponding pleat will alsofork at the same Department of the InteriorNational Park ServiceSaguaro National ParkDo animals use thesaguaro?

4 Saguaro cacti are host to a great varietyof animals. The gilded flicker and Gilawoodpecker excavate nest cavitiesinside the Saguaro s pulpy flesh. Whena woodpecker abandons a cavity, elfowls, screech owls, purple martins,finches and sparrows may move birds, like the Harris s and red-tailed hawks, also use the Saguaro fornesting and hunting platforms. Theirstick nests are constructed among thearms of a large Saguaro . In turn,Do humans use thesaguaro?In late April through early June, thetops of the Saguaro s trunk and armssprout a profusion of large, creamywhite flowers. Individual flowers openat night and close the following after-noon. To develop into fruits, they mustbe pollinated within this time is carried out by nectarfeeding bats, birds and fruit contains about 2,000 tinyblack seeds. When the fruit and seedsare eaten by a coyote or Cactus wren,the seeds pass through their digestiveHow does the saguaroreproduce?

5 Archeological evidence indicates thatthe Hohokam used the Saguaro in theirdaily life. The strong, woody ribs weregathered to construct the frameworkfor the walls of their , Saguaro ribs were used tocollect Saguaro fruits, which grow highup on the plant. Several ribs were tiedtogether with a cross piece at the there threats tothe Saguaro ?Reports of a Saguaro disease , popu-larized almost fifty years ago, persist,but saguaros are not subject to Saguaro is a long-lived Cactus ,most affected by long-term climatecycles of frost and drought. In actual-ity, the Saguaro is a common plant inthe Sonoran Desert, not an endan-gered question, the biggest threat tothe Saguaro is our rapidly expandingEven when Saguaro cacti grow in theirnormal form, they rarely grow sy m -metrically. Saguaros sometimes grow inodd or mis-shapen forms.

6 The grow -ing tip occasionally produces a fan-like form which is referred to ascrested or cristate. Though thesecrested saguaros are somewhat rare,over 25 live within the boundaries ofthe park. Biologists disagree as to whysome saguaros grow in this unusualform. Some speculate that it is a geneticmutation. Others say it is the result of alightning strike or freeze damage. Atthis point we simply do not know whatcauses this rare, crested are somesaguaros crested?Gila WoodpeckerLesser Long-nosed Batravens and great horned owls may takeover an abandoned hawk cacti also provide a valuablesource of food for animals. In latesummer, ripening fruit provides mois-ture and an energy-rich food during atime of drier areas of the Sonoran Desert,pack rats, jackrabbits, mule deer andbighorn sheep will also eat the Saguaro sflesh when other water sources are unharmed and are distributedthroughout the desert.

7 However, if theseeds are eaten by a dove or quail, theywill be completely consumed in thedigestive is estimated that a Saguaro can pro-duce some 40 million seeds during itslifetime. However, few will survive tobecome a seedling. Fewer still willbecome an adult. The low survival rateof seedlings is due to drought, pro-longed freezing and animals population. The developmentof new homes in the Tucson area hasresulted in a tremendous loss ofsaguaro habitat. With this influx ofpeople has come another threat to thesaguaro-exotic plants. Exotic plantsalmost always out-compete nativeplants for the limited resources of waterand nutrients. They have also led to anincrease in wildfires, which harm or killnative vegetation, including YOUR AMERICAT hese long poles were used to knockripe fruit down from the top of theplants.

8 It would then be gathered to Tohono O odham continue togather Saguaro fruit in this use the sweet fruits to makeceremonial wine, jelly and also use the seeds as chickenfeed.