Deltoid Spurge

Chamaesyce deltoidea ssp. deltoidea

Description

Deltoid spurge is an herbaceous, mat-forming plant, with wiry stems, prostrate or slightly ascending from a woody taproot. The triangular to oval leaves are only about 0.2 in (0.5 cm) long. Flowers are unisexual; male and female flowers are arranged together in a cup-like structure. The three-seeded fruits are only about 0.08 in (2 mm) long. Leafing occurs year-round; budding, antithesis, and fruiting occur from May to November.

This species has been classified elsewhere in the scientific literature as Chamaesyce deltoidea ssp. deltoidea. Federal listing of this plant encompasses two recognized varieties: Euphorbia deltoidea var. deltoidea (essentially hairless), and E. deltoidea var. adhaerens (hairy on the stems, leaves, and capsules). A near relative, wedge spurge (E. d. serpyllum ), restricted to Big Pine Key (Monroe County), Florida, is also a candidate for federal listing.

Habitat

Deltoid spurge grows in poorly developed soils composed mainly of a thin layer of sand over a substrate of porous limestone known as Miami oolite (a type of dolomite). The habitat occurs as a narrow low ridge that is markedly different from the surrounding marshes and wet prairies that dominate this part of Florida. Predominant vegetation is southern slash pine with an understory of saw palmetto, silver palm, poisonwood, rough velvetseed, and wax myrtle. Large numbers of endemic pine rockland plants are present in the understory.

Distribution

This species formerly ranged throughout the pine rockland, a habitat extending from southeastern Broward County to Long Pine Key in Everglades National Park along the South Florida Limestone Ridge at elevations of about 10 ft (3.5 m).

Both varieties of E. deltoidea appear to be restricted remnant pine rockland habitat in Dade County. E. deltoidea var. deltoidea occurs at eight sites in the Coral Gables-South Miami-Perrine area, while the variety adhaerens is found at two sites in the Homestead-Goulds area. Population figures were not published, but fewer than 50 plants of either variety were thought to survive in 1989.

A single deltoid spurge plant was discovered in 1987 on the 300-acre (121.4-hectare) Deering Estate, a preserve acquired jointly by Florida's Conservation and Recreation Lands Program and the Dade County Park and Recreation Department.

Threats

In general, pine rockland habitat is a vanishing biological community. Urbanization has overtaken much of the South Florida Ridge, particularly in Dade County. Fire has been suppressed in surviving tracts of habitat. Suppression of fire results in an increase of tropical hardwood hammock vegetation at the expense of pine rockland vegetation. The succeeding vegetation is characterized by oaks, gumbo-limbo, strangler fig, poisonwood, and wild tamarind. Controlled burning at three-to 10-year intervals is needed to maintain the distinctive pine rockland community.

Conservation and Recovery

In 1986, the U. S. Army submitted a management plan for an extensive section of pine rockland forest that occurs within the boundaries of its reserve training facility near Miami. This plan will protect deltoid spurge by restricting foot traffic in the pinelands, by initiating controlled burning on a periodic basis, and by monitoring population changes for the species. The U. S. Fish and Wildlife Service will provide technical assistance to the Army concerning its management of the property.

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

Burch, D. 1966. "Two New Species of Chamaesyce (Euphorbiaceae). New Combinations and a Key to the Caribbean Members of the Genus." Annals of the Missouri Botanical Garden 53:90-99.

Shaw, C. 1975. "The Pine and Hammock Forest-lands of Dade County." Report to Dade County, Florida, County Manager.

U.S. Fish and Wildlife Service. 1985. "Endangered and Threatened Status for Five Florida Rockland Plants." Federal Register 50:29345-29349.

U.S. Fish and Wildlife Service. 1988. "Recovery Plan for Five Florida Pine Rock Plant Species." Atlanta. 18pp.

Ward, D. B. 1979. Rare and Endangered Biota of Florida. Vol. 5, Plants. University Presses of Florida, Gainesville.