The saguaro takes 70 years to reach six feet, and a desert people call it family

A saguaro can take 70 years to reach six feet, which is about when it starts to grow thick branches, called arms. Its average age is 150 years, and some reach 200. The cactus (pronounced sah-WAHR-oh; Carnegiea gigantea) is the best-known plant of the Sonoran Desert, the area covering most of southern Arizona, a small part of California and, across the border, the Gulf of California region of Mexico. The National Park Service calls it North America’s greenest desert. Several park units in southern Arizona preserve the saguaro’s habitat, among them Saguaro National Park outside Tucson.

Saguaro cacti and other vegetation at Saguaro National Park. NPS photo.

A tall, ribbed column

A healthy saguaro is entirely green, with vertical ribs that cast shadows and give the trunk a fluted look, like the shafts of columns in classical architecture. The ribs come from a hardwood structure inside. Saguaros often grow beyond 30 feet. Most Sonoran Desert plants are stunted and hug the ground, so the saguaro is the tallest and most prominent of them, which has earned it the nickname king of the cactus family.

Saguaro cacti in the Sonoran Desert at Saguaro National Park. NPS photo.

Heat, rain and drought

Summer temperatures often top 120 degrees Fahrenheit. Saguaros grow faster where it is hot and wet than where it is hot and arid, and the eastern part of the Sonoran Desert, where Tucson and the park lie, is wetter than the western half, because prevailing weather brings warm, humid air up from the Gulf of California. Rain comes in brief bursts, up to five inches in a little over half an hour. The saguaro stores water from these storms for long periods, which lets a plant survive long droughts, and it visibly expands after absorbing rain. It can also survive an occasional winter frost or snowfall.

A plant seen as a person

Saguaros are often compared to trees, but more often described in human terms, with arms that seem raised in greeting or hanging in defeat. The Park Service says native peoples held this human-centered view for centuries before the Spanish first traveled through the desert. The various O’odham peoples, the Tohono, Akimel and Hia’Ced, still refer to individual saguaros as ancestors and family members. The cactus is central to many of their legends and religious ceremonies, and they have worked to increase protections for it.

Native peoples have long used almost every part of the plant. The name “saguaro” is a Hispanized version of the O’odham word Ha:san. The fruit was eaten or made into a ceremonial wine with the consistency of syrup, and the seeds, which are high in protein, were ground. Ribs from dead saguaros served as building material and for making tools and traps and starting fires, and can still be seen in traditional architecture at Saguaro National Park and nearby Organ Pipe Cactus National Monument. O’odham peoples still harvest the fruit with a long rib tied to a smaller crossbar, a tool called a kukuipad, and the harvest in the middle of summer marks the start of the O’odham new year.

Protection

The saguaro is protected in Arizona, where state cactus laws prevent theft or destruction and a permit is required to move one that interferes with private construction. Its white blossoms are the Arizona state flower, and visitors flock to southern Arizona between May and June when they bloom.

Blooms on a short saguaro arm. NPS photo.

A changing desert

The Sonoran Desert is growing hotter and drier with a changing climate. Saguaros thrive in hotter weather, and scientists have predicted an expansion of the plant’s range, but climate change also brings uncertainty. In 2020 a record number of wildfires killed thousands of saguaros, and invasive plants such as buffelgrass have created a more flammable landscape that fuels such fires. The desert also relies on annual monsoons that have become less predictable: a record amount of rain in 2018 caused widespread flooding and destruction, and in other years the rains have not come at all. The Park Service says the saguaro is far from endangered, but its home is threatened by climate change, and the park works with Tucson-based organizations on research and education.

Young and mature saguaros at Saguaro National Monument, Arizona. NPS History Collection.

Sources

• National Park Service, Saguaro National Park, “Saguaro Cacti at Saguaro National Park,” https://www.nps.gov/articles/000/sagu-saguaro-cacti-plant-story.htm; rewritten in hubnx’s own words.