Arizona Agave

Agave arizonica

Description

Arizona agave is a succulent with flattened, globular leaves that grow radially from a base to form a plant about 12 in (30 cm) high and 16 in (41 cm) broad. The plant puts up a slender, branching flower stalk up to 12 ft (3.6 m) high that bears small, pale-yellow, jar-shaped flowers. It sets seed infrequently. Fruiting occurs in August; seed and fruit dispersal occurs in November and December. Seeds are disseminated in a capsule.

The Arizona agave may be of recent hybrid origin. Hybridization within this genus sometimes occurs where the ranges of related species overlap. Since its discovery and description, however, Arizona agave has maintained its unique characteristics and is considered a distinct species.

Habitat

Arizona agave is found along the stony creek bottoms and atop the granite hills of the New River Mountains, Arizona, at an elevation of 3,000-6,000 ft (915 to 1,830 m). The surrounding vegetation is chaparral—a transitional zone between oak-juniper woodland and mountain mahogany-oak scrub. The soil is a gravelly loam derived from Mazatzal quartzite.

Distribution

Arizona agave is native to the New River Mountains north of Phoenix, Arizona, where Maricopa, Gila, and Yavapai Counties converge.

Arizona agave occurs as a series of localized, isolated populations scattered over about 65 sq mi (147.6 sq km). Recently, this agave has declined from 19 known populations to 13 or fewer, all located in the New River Mountains. As of 1986, the total population numbered fewer than 100 plants.

Threats

Other species of agave are used as ornamental plants in private rock garden collections and are offered for sale by commercial traders. Arizona agave is attractive and in the past was often collected by persons looking for a garden plant, unaware that it is almost extinct in the wild. Some plant traders, while aware of its rarity, collect it anyway. Arizona agave reproduces so slowly that it cannot repopulate areas that have been picked over by collectors.

Cattle eating or breaking agave stalks is the greatest threat to sexual reproduction. Cattle also eat the inflorescence, and in one field study of 30 plants, 13 had broken inflorescence stalks and only three had developed to full inflorescence. The agave snout weevil larvae uses the agave as a host plant, destroying its reproductive capability. Deer also eat flowering stalks and rodents eat young plants.

Conservation and Recovery

All populations of Arizona agave occur in the Tonto National Forest, which is managed by the U.S. Forest Service. Federal law prohibits Arizona agave's removal or destruction, but these prohibitions have been difficult to enforce because of a shortage of personnel, and because other agaves may be taken.

By freely cloning and seeding, the Arizona agave improves its sexual regeneration. Cultivated propagation will reduce the pressure on wild populations, as will the fencing and monitoring of agave habitat.

Contact

Regional Office of Endangered Species
U.S. Fish and Wildlife Service
P.O. Box 1306
Albuquerque, New Mexico 87103
http://southwest.fws.gov/

References

Gentry, H. S. 1970. "Two New Agaves in Arizona."Cactus and Succulent Journal 42(5): 223-225.

Kearney, T. H and R. H. Peebles. 1951. Arizona Flora. University of California Press, Berkeley.

Phillips, B. G., and N. Brain. 1980. "Status Report onAgave arizonica." U.S. Fish and Wildlife Service, Albuquerque.

U.S. Fish and Wildlife Service. 1987. "Endangered and Threatened Species of Arizona and New Mexico (with 1988 addendum)." U.S. Fish and Wildlife Service, Albuquerque.