Virginia Spiraea

Spiraea virginiana

Description

Spiraea virginiana (Virginia spiraea) bears cream-colored flowers on branched and flat-topped axes. This shrubby plant grows from 2-10 ft (0.6-3 m) tall and has arching, upright stems. Its alternate leaves are of different sizes and shapes. Spiraea spreads clonally and forms dense clumps which spread in rock crevices and around boulders. Flowering occurs in June and July.

Habitat

Virginia spiraea is unique because it occurs along rocky, flood-scoured riverbanks in gorges or canyons. Although it is an unusual requirement, flood scouring is essential to this plant's survival because it eliminates taller woody competitors and creates riverwash deposits and early sucessional habitats. These conditions are apparently essential for this plant's colonization of new sites. Spiraea is found in thickets. Common woody vine associates include fox grape; summer grape; riverbank grape; winter grape; graybark or pigeon grape; possum grape; sand grape; and muscadine or scuppernong. Other plant associates include royal fern, yellow ironweed or wing-stem; ninebark; smooth alder or brookside alder; silky cornel or kinnikinnik; and shrubby yellowroot. The bedrock surrounding spiraea habitat is primarily sandstone and soils are acidic and moist. Spiraea grows best in full sun, but it can tolerate some shade. One population in West Virginia inhabits a disturbed wetland habitat near a road.

Distribution

The species has 24 population sites in six states— West Virginia, Virginia, Tennessee, North Carolina, Kentucky, and Georgia. Thirteen of these populations host less than 10 plant clumps; eight sites have 10-50 clumps, and only three sites have more than 50 clumps. West Virginia has the largest population with 5,700 plants.

Kentucky's populations are located alongside the Rockcastle River in Pulaski County and Sinking Creek in Laurel County. In Virginia, populations are located on the Russell Fork and Pound Rivers in Dickenson County; the New River in Grayson County; and the Guest River in Wise County.

West Virginia's populations are found on the Bluestone River in Mercer County; the Buchannon River in Upshur County; in a shrub-dominated, wet meadow in Raleigh County; and along the Gauley and Meadow Rivers in Nicholas and Fayette Counties.

Georgia has two populations: one on Rock Creek in Walker County, and one on Bear Creek in Dade County. In Tennessee, spiraea is known from the Nolichucky River in Unicol County; Abrams Creek and the Little River in Blount County; Cane Creek in Van Buren County; White Oak Creek in Scott County; Clifty Creek in Roane County; Daddy's Creek in Cumberland County; and Clear Fork in Morgan and Scott Counties.

North Carolina has populations on the South Fork of the New River in Ashe County; the Little Tennessee River in Macon County; the Nolichucky River in Mitchell and Yancey Counties; and the South Toe and Cane Rivers in Yancey County. Historic populations are known to have been extirpated from Fayette County in Pennsylvania; Graham and Buncombe Counties in North Carolina; Fayette and Monongalia Counties in West Virginia; and Blount County, Tennessee. The U.S. Fish and Wildlife Service also considers this species threatened in Ohio.

Threats

Virginia spiraea faces a variety of threats. Most extirpated populations were eliminated by reservoir construction, and this is still a threat. Although spiraea needs some flooding to maintain its habitat requirements, severe flooding or inundation caused by dams would eliminate the species. Suitable habitat has disappeared throughout the range, either because of severe flooding or water stabilization which reduces scouring. A population in Monongalia County, West Virginia was one of the sites eliminated by dam construction. Several other man-induced alterations threaten most populations, especially in West Virginia. The state's largest population, along the Gauley-Meadow Rivers, is threatened by a proposed hydroelectric facility. One population—the only known occurrence of spiraea along a roadside—may be affected by highway maintenance and construction. Extensive clearing or water-siphoning within river watersheds has also destroyed spiraea habitat. In addition, several current and historic sites have been altered or destroyed by reservoirs or road/railroad development. One of Georgia's two populations is at Cloudland Canyon State Park, which has a lot of tourist traffic and recreational activities. In Tennessee, the species is threatened by upland timbering and dumping.

Natural factors are also impacting the species. In several populations, insect damage, such as leaf removal and laceration by caterpillars, has been observed. A common pest, the copper underwing moth caterpillar, is known to have damaged one population. The reproductive capacity of spiraea also may be seriously impaired. To date, no seedlings have been observed at any locations, and mature seeds have been found at only a few. Most of the plants in the existing populations are old, with well-established root systems. Very few of the seeds collected from plant sites have ever germinated. Tests suggest that these seeds could germinate with sufficient mineral soil to take root. In addition, little information is available on spiraea life history, but findings suggest that each of the existing populations represents only one genotype. This means there are 24 distinct genotypes, and that colonization and new site establishment would be difficult. Possibly, new populations could be established during floods by clumps breaking off and becoming established downstream. However, the clumps would have to be deposited at an ideal habitat site, and severe flooding could destroy the original populations.

Conservation and Recovery

Because the establishment of new sites would be difficult, efforts must focus on maintaining existing populations. Three sites are being voluntarily protected by their private landowners who were notified by the Nature Conservancy or through State Heritage programs. Six sites are partially or completely federally owned and four sites are partially or completely located in state parks. These public agencies should be encouraged to develop conservation management plans. Cooperative protection agreements can be established with private landowners. Research on the species' life history should also be conducted, especially on genetics and the causes of the species' limited seed production.

Contacts

West Virginia Ecological Services Field Office
U. S. Fish and Wildlife Service
P. O. Box 1278
Elkins, West Virginia 26241-1278
Telephone: (304) 636-6586
Fax: (304) 636-7824

U. S. Fish and Wildlife Service
Regional Office, Division of Endangered Species
1 Federal Drive
BHW Federal Building
Fort Snelling, Minnesota 55111
Telephone: (612) 713-5360
http://midwest.fws.gov/

U. S. Fish and Wildlife Service
Regional Office, Division of Endangered Species
1875 Century Blvd., Suite 200
Atlanta, Georgia 30345
http://southeast.fws.gov/

U. S. Fish and Wildlife Service
Regional Office, Division of Endangered Species
300 Westgate Center Dr.
Hadley, Massachusetts 01035-9589
Telephone: (413) 253-8308 Fax: (413) 253-8308
http://www.northeast.fws.gov/

References

"Proposed Listings: Virginia Spiraea (Spiraea virginiana )" 1989. Endangered Species Technical Bulletin 18(8):5-6.

Rawinski, Thomas J. 1988. "Final Status Survey Report: The Distribution and Abundance of Virginia Spiraea (Spiraea virginiana )." Report to the U.S. Fish and Wildlife Service, Newton Corner, Massachusetts.

U.S. Fish and Wildlife Service. 15 June 1990. "Threatened Status Determined for Spiraea virginiana (Virginia Spiraea)." Federal Register 55 (116):24241-24246.