Maguire Daisy

Erigeron maguirei

Description

The Maguire daisy, Erigeron maguirei, is a low-growing perennial herb. Clumps of stems grow from fibrous roots, reaching 5 in (12.5 cm) in height. Oblong leaves are dark green. Each lightly furred stem bears between one and five ray flowers with white petals surrounding an orange center. Flowers bloom in June.

In Wayne County, Utah, to the south, what was considered to be a related species of Erigeron was described in 1983, and identified as E. maguirei var. harrisonii (as opposed to the subspecies E. maguirei var. maguirei, the original scientific name for the Maguire daisy). But taxonomic studies in the early 1990s documented populations formerly recognized as E. maguirei var. maguirei and E. maguirei var. harrisonii did not merit recognition as separate varieties, so that E. maguirei should be recognized as a species without infra-specific taxa. The studies concluded that the morphological differences previously used to distinguish the two varieties were ecotypic and not genetically based.

The Maguire daisy was originally listed as Endangered in 1985. But when the status of the entire species is considered, a larger number of individuals are involved than had been previously considered to comprise var. maguirei; thus, the U. S. Fish and Wildlife Service (FWS) reclassified the flower as Threatened in 1994.

Habitat

This species was originally found in sandy soil on dry, rocky canyon bottoms. Since its discovery, it is believed to have disappeared from these open areas and is now found in a more marginal habitat along the cliffs, rooted in crevices on sandstone ledges or among boulders. Habitat elevation is roughly 5,800 ft (1,770 m). This is a semi-arid pinyon pine and juniper zone, where plants such as the Utah serviceberry, single-leaf ash, skunkbush, and little-leaf mock-orange are often found.

Distribution

The Maguire daisy was first identified from Calf Canyon in 1940 and relocated in Pine Canyon, a branch of Calf Canyon, in 1980. These two populations no longer exist. This daisy was once more widespread along the canyon bottoms, but livestock grazing and off-road vehicles have contributed to its decline.

Recent status surveys of endangered, threatened, and other rare plants in the San Rafael Swell (1990) and Capitol Reef (1989) documented about 3,000 individuals of Maguire daisy occurring at 12 sites. These 12 sites are reproductively isolated, forming separate populations. Even with this number of individuals and populations, the species remains vulnerable to threats such as the loss of habitat and genetic viability.

Threats

Despite the reclassification of the Maguire daisy from Endangered to Threatened, due to the larger population of the combined subspecies, the FWS believes that the flower's long-term survival is tenuous, since a significant portion of its habitat is threatened by ongoing and potential habitat alteration from mineral development, recreational activities, and livestock trampling. The species exists in small, reproductively isolated populations vulnerable to inbreeding and the loss of genetic viability.

The habitat of Maguire daisy is threatened with modification or destruction by off-road vehicle use and mining claim assessment work. Off-road vehicle use is a potential threat to populations located in accessible washes. Uranium ore deposits are known to occur within the species' habitat. Annual assessment work on uranium claims and other minerals is adversely impacting the species and its habitat. Any future development of these mineral deposits or associated surface disturbances could be detrimental to the species and its habitat.

Additionally, human and livestock trampling are known to adversely impact individual plants. Human foot traffic off established trails in Capitol Reef National Park is affecting one population. Trampling from human foot traffic is a potential threat to the species throughout its scenic canyon habitat in the San Rafael Swell and Capitol Reef areas. Livestock trampling has affected all populations, including those in Capitol Reef National Park. Unlike most national parks, Capitol Reef National Park is not closed to livestock grazing. Livestock trampling negatively impacts individual plants growing in accessible wash bottoms. This results in the species being restricted to less suitable habitat in the sandstone crevices of the adjoining slickrock canyon walls.

Conservation and Recovery

Provisions of the Endangered Species Act require the Bureau of Land Management (BLM) to consider the welfare of the Maguire daisy in its management plan for public lands in the region and to take steps to recover the plant. Recovery efforts have included restricting off-road vehicle access in portions of the canyons and fencing potential habitat on the canyon bottoms. The BLM is also responsible for supervising mining claims in the region and limiting disturbance caused by mineral exploration.

The FWS determined that designation of critical habitat is not prudent for the daisy, since such a designation would entail publishing a detailed map and description of critical habitat in the Federal Register, which could expose the species to threats of vandalism. Moreover, it decided that few additional benefits would be provided to the species by designation of critical habitat since most of the small, isolated populations are located on federal lands. The FWS and BLM are aware of the occurrence of Maguire daisies on lands under their jurisdiction and of their legal obligation to protect listed plants.

Contact

Regional Office of Endangered Species
U.S. Fish and Wildlife Service
P.O. Box 25486 Denver Federal Center
Denver, Colorado 80225
http://www.r6.fws.gov/

References

Cronquist, A. 1947. "Revision of the North American Species of Erigeron, North of Mexico." Brittonia 6(2):121-302.

Heil, K.D. 1989. "A Vegetation Study of Capitol Reef National Park-Endangered, Threatened, Rare, and Other Plants of Concern at Capitol Reef National Park." National Park Service, Torrey, Utah.

Kass, R.J. 1990. "Final Report-Habitat Inventory of Threatened and Endangered and Candidate Plant Species in the San Rafael Swell, Utah." Bureau of Land Management, Salt Lake City, Utah.

Welsh, S. L. 1983. "A Bouquet of Daisies (Erigeron, Compositae). Great Basin Naturalist 43(2):365-368.

Welsh, S. L. 1983. "Utah Flora: Compositae (Asteraceae)." Great Basin Naturalist 43(2):179-357.