Cumberland Rosemary

Conradina verticillata

Description

Cumberland rosemary is a small shrub which is only known from the banks of short reaches of three river systems in north-central Tennessee and adjacent Kentucky. Cumberland rosemary is about 1.5 ft (0.5 m) high with reclining branches that spread over the sandy or gravelly surface of sandbars and stream banks. The leaves are about 1 in (2.5 cm) long, very narrow, and arranged in tight bunches that appear as whorls around the stems. The 0.5 in-(1.3-cm) long flowers are purple, lavender, or occasionally white in color and are borne in leaf-like clusters of bracts at the ends of the stems. Flowers appear from mid-May to early June. After flowering four small, dark brown nutlets develop as the fruit matures.

Habitat

Cumberland rosemary's habitat is always in close association with the floodplain of watercourses. Specific areas supporting the species include boulder bars, sand bars, gravel bars, terraces of sand on gradually sloping river banks and islands, and pockets of sand between large boulders on islands and stream banks. All sites exhibit the following characteristics: (1) Open to slightly shaded conditions. Plants growing in full sun always produce more flowers; (2) Moderately deep, well-drained soils, consisting of pure sand or a mixture of sand and gravel with no visible organic matter; (3) Periodic flooding that is forceful enough to maintain the open condition of the sites; (4) Topographic features such as long, narrow channels or depressions on gravel bars, bank terraces, or large boulders that enhance sand deposition and to some degree protect the plants from the full force of the flooding and help in their establishment.

Woody plants growing in the shrubby vegetation adjacent to the sites supporting Cumberland rosemary include Alnus (alder); Cephalanthus (buttonbush); Chionanthus (fringe-tree); Cornus (dog-wood); Hamamelis (witch hazel); Itea (Virginia willow); Kalmia (laurel); Lyonia (fetter-bush); Rhododendron (Rhododendron); and Viburnum (no common name). The herbaceous associates growing with the species include the grass Calamovilva arcuata (no common name) and the herb Marshallia grandiflora (no common name) which are Category 2 plants on the U.S. Fish and Wildlife Service's list of species under review for possible addition to the Federal list of endangered and threatened species. Other herbaceous associates include: the common grasses Andropogon gerardii (no common name); Elymus virginicus (no common name); and Sorghastrum nutans (no common name); and the herbs Aster linariifolius (no common name); Coreopsis pubescens (no common name); Hypericum spp; (hypericum); Liatris microcephala (no common name); Phlox glaberrima (phlox); Pycnanthemum tenuifolium (no common name); Silphium trifoliatum (no common name); Thalictrium revolutium (no common name), and Veronicastrum virginicum (no common name).

Distribution

Forty-four occurrences of Cumberland rosemary have been reported in Tennessee, comprising three distinct populations: one along the South Fork Cumberland River and its tributaries in Morgan, Scott, and Fentress Counties; one along the Caney Fork River in Cumberland and White Counties; and, one along the Obed River System in Morgan and Cumberland Counties. Somers indicated that although the colonies in each of these populations are scattered along extended reaches of their respective river systems, the pollinators for each population can travel readily between colonies. Since all colonies within each river system can interbreed, they are biologically just one population.

Four colonies of Cumberland rosemary have been reported in Kentucky. All of the Kentucky colonies are along the South Fork Cumberland River in McCreary County. The Kentucky colonies therefore should, if the population definition used in Tennessee is followed, be considered part of the South Fork Cumberland River population of Tennessee.

Threats

The three known naturally occurring populations of Cumberland rosemary all occur in close proximity to rivers on the Cumberland Plateau in north-central Tennessee and adjacent Kentucky. Its distribution has probably been reduced by such factors as dam construction and the general deterioration of water quality resulting from silt and other pollutants contributed by coal mining, poor land use practices, and waste discharges. Many of these factors continue to impact the species and its habitat. Because the colonies inhabit only short river reaches, they are vulnerable to extirpation from accidental toxic chemical spills. Direct habitat destruction by recreational visitors to the species habitat is a significant threat to its survival. Hikers, campers, white-water enthusiasts, and off-road vehicles users all impact the species and its habitat. Visitation to the Big South Fork National River and Recreation Area has increased dramatically in the past few years. Visitors to the Recreation Area increased from 120,000 in 1986 to 730,000 in 1989. Increased use of the area will continue to adversely impact aquatic and riparian species.

There is commercial trade in Cumberland rosemary. Conradina are easily propagated and are in cultivation. This commercial trade, provided that it is dependent upon plants propagated from plants in cultivation, should not adversely affect the species in the wild. Usually, wild species that can be easily cultivated are less likely to become victims of illegal trade. Many of the wild colonies are small and cannot support collection of plants for scientific or other purposes. Inappropriate collecting from plants in the wild is a threat to the species.

Conservation and Recovery

In order to prevent the extinction of this species the following recovery actions must be taken: (1) Determine the relative importance of all known populations; (2) Provide the protection needed to ensure survival of populations determined to be essential to recovery of the species; (3) Provide the management needed to ensure survival of species; (4) Enforce laws prohibiting inappropriate trade and taking; and, (5) Protect genetic material through cultivation and seed banks.

Implementation of needed recovery actions will require research that: (1) Determines the habitat requirements of the species; (2) Determines the biology and life history of the species; (3) Determines the appropriate means of maintaining the species' habitat in a manner conducive to its survival; and, (4) Develops the techniques needed to reestablish the species at sites from which it has been extirpated.

Contacts

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

Asheville Ecological Services Field Office
U. S. Fish and Wildlife Service
160 Zillicoa St.
Asheville, North Carolina 28801-1082
Telephone: (828) 258-3939
Fax: (828) 258-5330

References

Gray, T. C. 1965. A Monograph of the Genus Conradina A. Gray (Labiatae). Unpublished Ph.D. Dissertation, Vanderbilt University, Nashville, Tennessee. 189 pp.

Jennison, H. M. 1933. "A new species of Conradina from Tennessee." Journal of the Elisha Mitchell Scientific Society 48268-269.

Patrick, T. S. and B. E. Wofford. 1981. "Status Report Conradina verticillata Jennison." Unpublished report to the Southeast Region U. S. Fish and Wildlife Service. 49 pp.