Saguaro Cactus

southwestlearning.org
sonoran desert
Saguaro Cactus
national park service
Sentinel of the Southwest
FACT SHEET
Background
The saguaro cactus, Carnegiea gigantea, is the largest cactus in the U.S., commonly reaching 40 feet in height. The saguaro provides both food and shelter for a variety of desert
species and plays an integral role in the culture of the Tohono
O’odham people. It has been written that the saguaro can be
ecologically connected to nearly every other organism in its
range, including humans.
Ecology
The saguaro cactus grows only in the Sonoran Desert of the
U.S. and Mexico. Its range is limited by freezing temperatures
and altitude.
The body and armlike branches of the saguaro are pleated
and ridged, with hard spines and bristles. In May and June,
white flowers bloom, followed by bright-red fruits that may
each contain up to 2,000 small black seeds. Composed mostly
of water (75–90% of the plant’s mass), saguaros may weigh
more than 6 tons.
Saguaro cacti are highly important to both animals and people.
Small birds excavate nest cavities inside the saguaro’s pulpy
California
Arizona
New Mexico
Texas
Mexico
Sonoran Desert (brown), with an overlay of the range of the saguaro
cactus (green).
10.1.2009
Saguaro cacti, Saguaro National Park.
flesh, and large ones build stick nests among its arms. Saguaro
flowers, fruit, and flesh variously provide nectar, moisture,
and food for birds, bats, mammals, reptiles, and insects. Archeological evidence indicates that the Hohokam people of
the modern-day Tucson area used the saguaro in their daily
lives. For the present-day Tohono O’odham, believed to be
descendants of the Hohokam, the saguaro is a sacred plant,
used for both ceremony and sustenance.
Saguaros are slow-growing. In Saguaro National Park, a saguaro grows between 1 and 1.5 inches in the first eight years
of its life; branches normally begin to appear at 50–70 years
of age. In drier areas, it may take up to 100 years before the
branches appear. Saguaros begin to produce flowers at around
35 years of age, and reach adulthood at about 125 years of age.
The average life span of a saguaro is probably 150–175 years,
but some plants may live more than 200 years.
Status and Threats
The saguaro is a common plant in the Sonoran Desert, and
is not an endangered species. The biggest threats to its current status are anthropogenic: loss of habitat and exotic-plant
introduction. Exotic plants, particularly buffelgrass, fountain
grass, and red brome, are problematic because they can both
outcompete the saguaro and increase the risk of fire in a landscape not adapted to it. Therefore, management of fire and exotic plants in Saguaro NP is crucial to maintaining a naturally
functioning saguaro population. Other threats to the saguaro
include vandalism, attempted transplant, and theft.
Prepared by Alice Wondrak Biel, Sonoran Desert Network