Kearney's Blue-star

Amsonia kearneyana

Description

Kearney's blue-star, Amsonia kearneyana, is a herbaceous perennial which grows to a height of 16-32 in (40-60 cm). Up to 50 erect stems arise from a thick, woody root, giving mature plants a hemispherical appearance. The alternate leaves are hairy and lance-shaped. Pale blue to white flowers appear in terminal clusters in April or May.

The species was first collected in 1926 and was long considered a sterile hybrid. In 1982 it was recognized as a valid taxon, based on distinctive morphological characteristics and the viability of more than 50% of seed.

Habitat

Kearney's blue-star grows in alluvial deposits of small boulders or cobbles that line a dry, semidesert wash. Associated plants are net-leaf hackberry, Arizona walnut, Mexican blue oak, and catclaw acacia.

Distribution

The species is known only from a single population in a canyon on the western slopes of the Baboquivari Mountains in Pima County, Arizona. The canyon is on the Tohono O'odham (formerly Papago) Indian Reservation. When surveyed in 1982, the entire population consisted of 25 plants. By 1988 the species had declined to only eight plants. A glimmer of hope remains however: After transplanting, the Arizona-Sonora Desert Museum propagated seedlings from seed and the new plants are being carefully monitored.

Threats

The principal threats to Kearney's blue-star are habitat degradation caused by livestock grazing and the apparent failure of remaining plants to successfully reproduce. Although livestock do not feed on the plant, overgrazing causes a decline in plant species diversity which may be accompanied by a reduction in pollinators. Overgrazing also increases the potential for soil erosion and flooding, a possible catastrophe for a species of such limited numbers and distribution.

There are troubling signs that the species may not be capable of sustaining a naturally reproducing population. Of the 25 plants found in 1982 only one was a seedling. In 1986 mature plants had only a few developing fruits, and those contained an unusually small number of developing seeds. The cause of this reproductive failure is not known, but possible explanations include extremes of temperature and soil moisture, absence of pollinators, and destruction of seedlings by livestock. Insects are also a possible cause of seed destruction. Stinkbugs (Chlorochroa ligata ), known to destroy the seeds of the related A. grandiflora, occur with the range of Kearney's blue-star.

Conservation and Recovery

The Bureau of Indian Affairs (BIA) is responsible for issuing grazing permits on tribal lands. The U. S. Fish and Wildlife Service (FWS) is currently working with the BIA and the Tohono O'odham Nation to secure protection and a management plan for this extremely Endangered species.

Hopes of preserving the species lie in horticultural science; the Sonoran Desert Museum in Tucson has seeded transplanted individuals, and it is hoped that lasting new populations can be grown from these rare seeds. The 1992 FWS Recovery Plan for the species has as its primary objective the maintenance of enough viable populations in a natural habitat to ensure that the species is safe from extinction. The species will be considered for reclassification from endangered to threatened when ten geographically distinct, self-sustaining, natural populations are protected in Arizona. These ten populations must represent the geographic range of the species.

The recovery plan outlines main actions for saving the species, including identifying and protecting natural and introduced populations; assessing the status of natural, reintroduced, and ex situ populations; researching and observing the populations to describe the species' habitat requirements, and modify management as appropriate; surveying for new populations; establishing a sufficient number of reintroduced populations to meet the downlisting criteria; establishing an ex situ conservation program; and information and education programs to inform the public about the importance of preserving and protecting this rare plant.

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

McLaughlin, S. P. 1982. "A Revision of the Southwestern Species of Amsonia (Apocynaceae)." Annals of the Missouri Botanical Garden. 69(2):336-350.

Phillips, B. G. and N. Brian. 1982. "Status Report onAmsonia kearneyana." U.S. Fish and Wildlife Service. Albuquerque, New Mexico.

Turner, R. M. and D. E. Brown. 1982. "SonoranDesert Scrub." In D. E. Brown, ed., "Biotic Communities of the American Southwest-United States and Mexico." Desert Plants 4:181-221.

U.S. Fish and Wildlife Service. 1992. "Kearney's Blue Star (Amsonia kearneyana) Recovery Plan."U.S. Fish and Wildlife Service, Albuquerque.