Scrub Mint

Dicerandra frutescens

Description

Scrub mint, Dicerandra frutescens, is a strongly aromatic plant ranging up to 1.6 ft (0.5 m) tall, with clusters of erect, supple stems growing from a woody root. Opposite leaves, about 1 in (2.5 cm) long, are narrowly oblong with untoothed margins and blunt tips; leaves are covered with conspicuous sunken glands, a distinctive characteristic. Leaves are larger at the base of the plant. Smaller leaves occur with flower buds at each stem node.

Flowers are borne on short stalks in pairs at intervals along the stems. The lipped, tubular corolla of the flower is about 0.6 in (1.5 cm) long. Flower color is white or pale pink with purplish-rose dots. Four large stamens protrude from the corolla. Each half of the anther (pollen-bearing part) is tipped by a horn or spur.

Habitat

Scrub mint grows primarily on well-drained fine sand soils along the margins of sand pine forests. It favors bare sandy areas in full sunlight.

Distribution

Scrub mint is endemic to Highlands County, Florida. It occurs in the Southern Central Florida Ridge Sandhill geographical province.

Threats

The mint's favored scrub/sandhill habitat has been reduced by more than 75% in Highlands County, mainly by agricultural and residential development. The plant has disappeared from three former sites in Highlands County; one site was planted in citrus groves, another clear-cut for meadowland, and the third was bulldozed for a housing subdivision.

Scrub mint is now known from a limited area of the Lake Wales Ridge in Highlands County. Of four known sites, one healthy population grows in fire lanes among scrub pine on the Archbold Biological Station. These fire lanes are largely undisturbed by people, except for an occasional maintenance vehicle. A site in the Lake June in Winter area in the vicinity of Lake Placid was sold to developers in 1987. Another site along U.S. 27 is considered a prime location for a housing development.

Scrub mint is also dependent on insects for pollination, and changes in the insect population have impacted this plant.

Conservation and Recovery

The U. S. Fish and Wildlife Service (FWS) Recovery Plan recommends that new populations of scrub mint be established in protected habitats along the Lake Wales Ridge. The FWS will negotiate with landowners to protect privately-held sites. Controlling successional growth by fire or mowing is necessary prevent the shading out of mint populations.

Biologists are currently researching techniques of seed storage and propagation, and a commercial nursery in South Carolina has successfully grown the scrub mint from cuttings. In 1987 three plants were sprouted from seed at the National Herb Garden in Washington, D. C. These plants will be used to establish a cultivated stock for eventual reintroduction into suitable tracts of habitat.

If protected, self-sustaining populations can be established within its historic range, the FWS will consider reclassifying the scrub mint as threatened.

Contact

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

References

Kral, R. 1982. "Some Notes on Dicerandra (Lamiaceae)." Sida 9(3):238-262.

U. S. Fish and Wildlife Service. 1987. "Recovery Plan for Three Florida Mints." U. S. Fish and Wildlife Service, Atlanta.

Wunderlin, R. P. 1984. "Status Report on Dicerandra frutescens Shinners." Report. U. S. Fish and Wildlife Service, Jacksonville.