Species Brief
Carnegiea gigantea, saguaro
Written
July, 2026
Contributors
Taryn R. Brahmsteadt - 1st Compiler, Ilana L. Abrahamson - 1st Editor
Brahmsteadt, Taryn R., compiler. 2026. Carnegiea gigantea, saguaro. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Missoula Fire Sciences Laboratory (Producer). Available: https://research.fs.usda.gov/feis/species-briefs/cargig
Scientific Name
Carnegiea gigantea
Common Names
saguaro
pitahaya
giant cactus
sahuaro
FEIS Lifeform Type
Cactus
Tree
Kingdom
Plantae
Class
Magnoliopsida (Dicot)
Order
Caryophyllales
Family
Cactaceae
Genus
Carnegiea
Nativity
Native
Invasiveness
Noninvasive
This Species Brief is a concise summary of the biological, ecological, and fire‑related characteristics of an individual species derived from a Fire Effects Information System (FEIS) Species Review. Table 1 is derived from a standardized template and highlights these characteristics.
| Attribute | Characteristic | Justification | Source |
|---|---|---|---|
| Biological characteristics | |||
| Life form | Cactus | Saguaro is a perennial cactus with semi-woody to woody stems and is the largest columnar cactus species in the United States, commonly reaching 10 m tall. | FEIS: Summary [1] |
| Typical lifespan | 101-200 years | Saguaro lifespan is thought to be typically around 150 to 200 years. The oldest known saguaro was estimated to be nearly 300 years old. | FEIS: Stand Structure [1] |
| Life cycle | Perennial | Saguaro is a perennial cactus with semi-woody to woody stems. | FEIS: Aboveground Description [1] |
| Drought tolerance | High | Water stored almost entirely in the stem allows plants to withstand long periods of drought and water losses of 23% to 54% of fully hydrated weight. | FEIS: Aboveground Description [1] |
| Rooting depth | Shallow | The root system consists of a short (~1 m) tap root and shallow horizontal roots concentrated within the top 15 cm of soil and extending up to 30 m from the parent plant. | FEIS: Belowground Description [1] |
| Tree bark thickness at maturity | N/A | Saguaro is a cactus, not a tree. | FEIS: Summary [1] |
| Tree that sheds low branches | N/A | Saguaro is a cactus, not a tree. | FEIS: Summary [1] |
| Reproduction and Regeneration | |||
| Adventitious buds | None | Saguaro reproduces sexually and regenerates from seeds. It does not reproduce vegetatively, nor does it sprout following top-kill. | FEIS: Regeneration Processes [1] |
| Time to reproductive maturity | 21-50 years | Most saguaro plants begin producing fruit when they reach about 2 to 2.5 m tall, about 30 to 50 years old. | FEIS: Summary [1] |
| Soil seed bank longevity | Transient (<1 year) | Saguaro does not have persistent seed banks. Seeds are intolerant of drought, are heavily predated, and quickly deteriorate in the soil. However, some seeds may remain viable until the following summer monsoon. | FEIS: Seed Banking [1] |
| Serotinous cones | N/A | Cacti have no cones. | FEIS: Regeneration Processes [1] |
| Seed dispersal mechanism | Animal; Gravity; Wind; Water | Animals play a primary role in dispersal of saguaro seeds. Seeds are also dispersed by gravity, wind, and water. | FEIS: Seed Dispersal [1] |
| Seed dispersal distance | Short*; Medium*; Long* | Saguaro seeds are consumed and dispersed by a variety of animals, as well as by gravity, wind, and water; distances are not quantified, but seeds are likely dispersed from short to long distances from the parent plant. | FEIS: Seed Dispersal [1] |
| Typical requirements for seedling establishment | Nurse plant/object; Shade | Saguaro seedlings are often associated with nurse plants or rocks. Seedlings and young plants require shade, typically provided by a nurse plant. | FEIS: Site Characteristics; Successional Status [1] |
| Successional Status | |||
| Shade tolerance | Shade intolerant* | Saguaro dominates late successional plant communities in full sun, although seedlings and young plants require shade, typically provided by a nurse plant. | FEIS: Successional Status [1] |
| Successional status | Late | Adult saguaro dominates late successional plant communities in full sun and is not likely to establish in early succession following stand-replacing disturbance, in part because of the lack of nurse plants. | FEIS: Successional Status [1] |
| Fire | |||
| Primary fire response(s) or adaptation(s) | Fire Sensitive | Saguaro is not considered fire adapted. It is easily damaged and often killed by fire, and postfire regeneration is limited. | FEIS: Fire Adaptations; Fire Management Considerations [1] |
| Germination is fire stimulated | Rarely/No | Germination requires adequate light, warm temperatures, and moisture within a few weeks after fruit ripens. There is no fire cue, and seeds do not persist in the soil. | FEIS: Germination [1] |
| Flowering/fruiting is fire stimulated | Rarely/No | Neither flowering nor seed production increase after fire. | FEIS: Plant Response to Fire [1] |
| Plant flammability | Low | Cacti do not usually combust. Saguaro is a succulent consisting of >85% water, so living plants do not typically contribute fuels for carrying wildland fires. | FEIS: Fuel Characteristics [1] |
| Early colonizer/recolonizer of burned or disturbed sites | Rarely/No | Saguaro is not likely to establish in early succession following stand-replacing disturbance, and several studies found no saguaro seedlings on burned areas monitored for several years after fire. However, saguaro seedlings may establish on burned sites after low severity fire. | FEIS: Successional Status; Plant Response to Fire [1] |
| Effect of fire exclusion on population | Different patterns throughout range | Fires were historically rare in Sonoran desert scrub communities, so excluding fire is likely to have minimal effects. However, at its upper elevational limit and adjacent to semi-desert grassland, where fire was likely frequent enough to prevent establishment and persistence of saguaro, fire exclusion coincident with a period of relatively cool, moist climate may have enabled saguaro establishment on sites where frequent fire had previously prevented it. Thus, fire exclusion could promote saguaro establishment. | FEIS: Fuel Characteristics [1] |
| Is this species typically managed with prescribed fire? | Rarely/No | Fire is generally considered harmful to saguaro communities. | FEIS: Fire Management Considerations [1] |
| Predominant historical fire frequencies of ecosystem where it most commonly occurs | Infrequent | Fire is considered to have been rare to absent in presettlement Sonoran Desert scrub communities, and mean historical fire intervals derived from LANDFIRE succession modeling are estimated to exceed 1,000 years. | FEIS: Fire Regimes; LANDFIRE Biophysical Settings [1] |
| Predominant historical fire severity where it most commonly occurs | Replacement | Because many of the dominant and characteristic species in Sonoran desert scrub communities are poorly adapted to survive fire or reproduce in the postfire environment, it is often assumed that any fires that did occur would have had high-severity effects. LANDFIRE models classify these rare or infrequent historical fires as high-severity, stand-replacement fires. | FEIS: LANDFIRE Biophysical Settings [1]; FEIS: Fire regimes of Sonoran desert scrub communities [2] |
| Predominant historical fire regime group where it most commonly occurs | 5 | Mean historical fire intervals derived from LANDFIRE succession modeling are estimated to exceed 1,000 years, with large, high-severity fires considered historically rare — consistent with fire regime group 5. | FEIS: Fire Regimes; LANDFIRE Biophysical Settings [1] |
| Alters historical fuel characteristics of ecosystems where it occurs | Rarely/No | Living saguaro do not typically contribute fuels for carrying wildland fires; the documented shift in fuel and fire regimes is driven by nonnative invasive grasses, not by saguaro. | FEIS: Fuel Characteristics [1] |
| Biophysical Setting | Mean Fire Interval (years) | Fire Severity Percent (%) | ||||||
|---|---|---|---|---|---|---|---|---|
| Code | Fire Regime Group | Low | Mixed | Replacement | All | Low | Mixed | Replacement |
| Series 11090 - Sonoran Paloverde-Mixed Cacti Desert Scrub | ||||||||
| 11090_4_13 | V-B | 1284 | 1284 | 0 | 0 | 100 | ||
| 11090_14 | V-B | 1056 | 1056 | 0 | 0 | 100 | ||
| 11090_15_25 | V-B | 1049 | 1049 | 0 | 0 | 100 | ||
| Summary | ||||||||
| Minimum | 1049 | 1049 | 0 | 0 | 100 | |||
| Maximum | 1284 | 1284 | 0 | 0 | 100 | |||
| Mean | 1130 | 1130 | 0 | 0 | 100 | |||
| Median | 1056 | 1056 | 0 | 0 | 100 | |||
| Percentage of fires in 3 fire severity classes, derived from LANDFIRE succession modeling. Replacement-severity fires cause >75% kill or top-kill of the upper canopy layer; mixed-severity fires cause 26%-75%; low-severity fires cause <26%. | ||||||||
| LANDFIRE. 2020. Biophysical settings models and descriptions, [Online]. Washington, DC: U.S. Department of Agriculture, Forest Service; U.S. Department of the Interior; U.S. Geological Survey; Arlington, VA: The Nature Conservancy, (Producers). Available: https://www.landfirereview.org/search.php [96496] | ||||||||
- Helmy, Olga. 2021. Carnegiea gigantea, saguaro. In: Fire Effects Information System, (Online). U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Missoula Fire Sciences Laboratory (Producer). Available: https://research.fs.usda.gov/feis/species-reviews/cargig
- Zouhar, Kristin. 2023. Fire regimes of Sonoran desert scrub communities. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Missoula Fire Sciences Laboratory (Producer). Available: https://research.fs.usda.gov/feis/fire-regimes/sonoran-desert-scrub
Last updated July 22, 2026