Cactus Habitat: Sonoran Desert

Jennifer Galas

Dozens of cactus species thrive in the diverse environment of Arizona's Sonoran Desert.

Sonoran Desert

Southern Arizona

The Sonoran Desert is the most biologically diverse of the four US deserts. It represents the northernmost end of the range for many Mexican cactus species, such as saguaro, organ pipe, and some Mammillaria—and the only place these cacti can be found in the US. A variety of elevations, providing different average temperature ranges, also contributes to the Sonoran Desert's species diversity. The desert experiences two rainy seasons: one in the summer that provides most of the soaking rainfall cacti need during their growing season, and one in the winter that is less intense but more widespread.

Threats to Sonoran Desert cactus populations include development, off-road vehicle recreation, and nonnative plants that not only compete for scarce resources but also increase the risk of fire. Desert cacti are not fire-adapted and entire populations of the slow-growing plants can be decimated by wildfire. Poaching of plants for horticultural trade is a concern, as is vandalism of saguaros.

Many plants in Arizona are protected by the Native Plant Protection Act, and groups of dedicated volunteers like the Tucson Cactus Rescue Program work to move saguaros and other rare desert plants away from proposed developments.

<i>Mammillaria grahamii</i>: Most members of <i>Mammillaria</i> grow in Mexico, but this species occurs as far north as Phoenix. They are common, but hard to spot because they're small and often nestled beneath other larger plants.

Mammillaria grahamii

Most members of Mammillaria grow in Mexico, but this species occurs as far north as Phoenix. They are common, but hard to spot because they're small and often nestled beneath other larger plants.

<i>Ferocactus wislizeni</i>: The Arizona barrel cactus can grow to 6 feet high. Thick curved spines protect the plant from herbivores, provide shade, and collect and funnel moisture from the air toward the base of the plant.

Ferocactus wislizeni

The Arizona barrel cactus can grow to 6 feet high. Thick curved spines protect the plant from herbivores, provide shade, and collect and funnel moisture from the air toward the base of the plant.

<i>Echinocereus triglochidiatus beneath Cylindropuntia fulgida</i>: Most desert plants eventually tolerate full sun, but youngsters owe their survival to the shade and shelter of larger desert dwellers.

Echinocereus triglochidiatus beneath Cylindropuntia fulgida

Most desert plants eventually tolerate full sun, but youngsters owe their survival to the shade and shelter of larger desert dwellers.

<i>Echinocereus rigidissimus</i>: A young "Arizona Rainbow Hedgehog Cactus" grows in the shelter of a nurse plant.

Echinocereus rigidissimus

A young "Arizona Rainbow Hedgehog Cactus" grows in the shelter of a nurse plant.

The iconic giant of the Sonoran Desert, the saguaro (<i>Carnegiea gigantea</i>) blooms in May. Saguaros can live for 200 years and grow to over 40 feet tall.

Saguaro in bloom

The iconic giant of the Sonoran Desert, the saguaro (Carnegiea gigantea) blooms in May. Saguaros can live for 200 years and grow to over 40 feet tall.

<i>Echinocereus engelmannii</i>: This "hedgehog cactus" is relatively common in extreme southern Arizona, particularly in Organ Pipe National Monument.

Echinocereus engelmannii

This "hedgehog cactus" is relatively common in extreme southern Arizona, particularly in Organ Pipe National Monument.

<i>Opuntia phaeacantha</i>: This cactus grows relatively quickly and is widespread. Like other cacti in the region, the fruits and stems of these cacti were important food sources for indigenous people.

Opuntia phaeacantha

This cactus grows relatively quickly and is widespread. Like other cacti in the region, the fruits and stems of these cacti were important food sources for indigenous people.

Saguaro "skeleton": When the giants die, they leave "ribs" of lignified tissue, used by early people as building material and to retrieve fruit from tall cacti.

Saguaro "skeleton"

When the giants die, they leave "ribs" of lignified tissue, used by early people as building material and to retrieve fruit from tall cacti.

This vista from the Phoenix Mountains Preserve shows Echinocactus, Ferocactus, cholla, and saguaro cactus.

 All images © Jennifer Galas

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