Carnegiea

Description

Carnegiea is a genus of large, columnar cacti native to the Sonoran Desert in North America. The most iconic species in this genus is the saguaro cactus (Carnegiea gigantea), which can grow up to 60 feet tall and live for over 150 years. These cacti are known for their distinctive arms that curve upward, which are actually branches that develop as the cactus ages. Carnegiea cacti are an important part of the ecosystem in the Sonoran Desert, providing food and shelter to a variety of animals.

Taxonomic Information

Appearance

Carnegiea cacti have a distinctive columnar shape, with a thick, woody stem covered in sharp spines. The stem can grow up to 18 inches in diameter and is typically covered in a waxy coating that helps the cactus retain water. As Carnegiea cacti age, they develop branches that curve upward, giving them a distinctive silhouette. These branches can number in the dozens and can grow up to 5 feet long. In the spring, Carnegiea cacti produce large, white flowers that can be up to 4 inches in diameter. These flowers are followed by edible red fruit that is an important food source for animals in the Sonoran Desert.

Care Guide

Carnegiea cacti are relatively easy to care for, but they do have specific requirements:

• Water: Carnegiea cacti are adapted to the dry conditions of the Sonoran Desert and should be watered sparingly. Water deeply once a month during the growing season (spring and summer) and reduce watering in the winter.
• Fertilization: Fertilize Carnegiea cacti once a year in the spring with a slow-release fertilizer specifically formulated for cacti.
• Soil: Carnegiea cacti require well-draining soil. Use a commercial cactus mix or make your own by mixing sand, perlite, and potting soil in a 1:1:2 ratio.
• Sunlight: Carnegiea cacti require full sun to thrive. Plant them in a location with at least 6 hours of direct sunlight per day.
• Hardiness Zones: Carnegiea cacti are hardy in USDA zones 9-11.

Common Pests & Diseases

Carnegiea cacti are generally resistant to pests and diseases, but they can be vulnerable to:

• Scale insects: These small, flat insects can attach themselves to the stems and branches of Carnegiea cacti and suck out their sap. Treat with a horticultural oil spray.
• Root rot: Overwatering can cause the roots of Carnegiea cacti to rot. Ensure the soil is well-draining and reduce watering in the winter.

Habitat

Carnegiea cacti are native to the Sonoran Desert, which spans parts of Arizona, California, and Mexico. They grow in arid regions with hot summers and mild winters. Carnegiea cacti are an important part of the ecosystem in the Sonoran Desert, providing food and shelter to a variety of animals, including desert bighorn sheep, Gila woodpeckers, and elf owls.

Question and Answer

Q: How long does it take for a Carnegiea cactus to grow its first arm?

A: Carnegiea cacti typically start to develop their first arm when they are between 50-75 years old.

Q: Are Carnegiea cacti endangered?

A: Carnegiea cacti are not currently listed as endangered, but they are protected by law in the United States and Mexico.

Q: Can I grow Carnegiea cacti indoors?

A: Carnegiea cacti are not well-suited for indoor growing, as they require full sun and dry conditions to thrive.

Q: Can I eat the fruit of a Carnegiea cactus?

A: Yes, the fruit of Carnegiea cacti is edible and is a traditional food of the Tohono O’odham people of the Sonoran Desert.

Related Plants

• Echinocactus grusonii (golden barrel cactus)
• Ferocactus cylindraceus (California barrel cactus)
• Mammillaria elongata (ladyfinger cactus)

References

• “Carnegiea.” Encyclopædia Britannica. Encyclopædia Britannica, Inc., n.d. Web. 10 Mar. 2021.
• “Carnegiea gigantea.” USDA Plants. United States Department of Agriculture, n.d. Web. 10 Mar. 2021.
• “Saguaro National Park.” National Park Service. U.S. Department of the Interior, n.d. Web. 10 Mar. 2021.