Dwarf-flowered Heartleaf

Hexastylis naniflora

Description

Dwarf-flowered heartleaf is a low-growing herbaceous plant, rarely exceeding 6 in (15 cm) in height. The evergreen, heart-shaped leaves, dark green and leathery, are supported by slender petioles (leaf stalks), rising from a rhizome. Inconspicuous, beige or dark brown flowers are jug-shaped and bloom at the base of the leaf petioles. Flowers occur from mid-March to early June and the fruit matures from mid-May to early July. The plant may be distinguished from close relatives by its small flowers and distinctive habitat.

Habitat

This species grows in narrow ravines or along the base of bluffs and hillsides that overlook bogs, marshes and small streams. It is restricted to moist, acidic soils and prefers partial sunlight. Habitat areas are typically heavily forested with mature stands of mixed hardwoods.

Distribution

Dwarf-flowered heartleaf is known from an eight-county area in the upper Piedmont of North Carolina and adjacent portions of South Carolina.Eleven populations of heartleaf are currently known from five North Carolina counties—Cleve-land, Catawba, Burke, Rutherford, and Lincoln.

Three Cleveland County sites support about 400 plants that are threatened by timbering or conversion of the habitat to pasture. A healthy population of more than 1,000 plants occurs at one site in Catawba County that is protected by Natural Areas Registry Program of the North Carolina Natural Heritage Program. Burke County harbors three populations in marginal habitat, totaling fewer than 1,000 plants. The site of the largest Rutherford County population, numbering more than 1,000 plants, is a registered natural area, but two smaller sites nearby are threatened by road construction. Of three populations that had been documented from Lincoln County, two were recently lost to logging and agricultural development, while the third population survives as a remnant of about 160 plants.

Currently, this species is known from 12 populations in three South Carolina counties—Cherokee, Greenville, and Spartanburg. One small population of about 150 plants survives in Cherokee County in habitat that has recently been degraded by road construction. Conversion of woodlands to pasture, logging, and urban expansion have limited the extent of all eight population sites in Greenville County. Numbers in these populations have declined to fewer than 800 plants. The largest population in Spartanburg, once numbering 4,000 plants, declined by nearly 65% when part of its habitat was flooded by a newly constructed reservoir. Two remnant populations have nearly been eliminated by construction of an interstate highway.

Threats

Although surviving populations of dwarf-flowered heartleaf are geographically dispersed, all are threatened by similar factors. In the past, bottom-land timber was clear-cut, and bogs and marshes were drained to create pasture for livestock, decreasing the amount of available habitat. Many bogs at the sources of streams have been dammed to create ponds for watering livestock. Conversion of habitat for agricultural uses continues. More recently, land has been cleared to support residential development, particularly near the city of Greenville, South Carolina. Associated construction of new reservoirs to supply the expanding human population and of new roads to handle the increased flow of traffic have claimed large tracts of former heartleaf habitat.

Conservation and Recovery

At some population sites, hardwood stands have grown so dense as to restrict sunlight, reducing the vigor of plants. Where these sites can be accessed, selective logging would improve light penetration. Only four populations are currently protected. The state natural heritage programs (under the direction of the Nature Conservancy) and the city of Spartanburg, South Carolina, are cooperating with the U. S. Fish and Wildlife Service to plan recovery for dwarf-flowered heartleaf.

Contact

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

References

Gaddy, L. L. 1980. "Status Report on Hexastylis naniflora Blomquist." Report. U.S. Fish and Wildlife Service, Atlanta.

Gaddy, L. L. 1981. "The Status of Hexastylis naniflora Blomquist in North Carolina." Report. Plant Conservation Program, North Carolina Department of Agriculture, Raleigh.

U.S. Fish and Wildlife Service. 1989. "Determination of Threatened Status of Hexastylis naniflora (Dwarf-flowered heartleaf)." Federal Register 54(71): 14964-14967.