Tiny Polygala

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Tiny Polygala

Polygala smallii

Status	Endangered
Listed	July 18, 1985
Family	Polygalaceae (Milkwort)
Description	Erect biennial with lance-shaped leaves and yellow-green flowers.
Habitat	Pine rockland.
Threats	Urbanization, fire suppression, competition with introduced plants.
Range	Florida

Description

Tiny polygala, Polygala smallii, is an erect biennial herb with short, branched or unbranched stems. The crowded, somewhat lance-shaped leaves are from 0.5-2 in (1.2-5 cm) long, and often form a rosette at the base of the plant. Small yellow-green flowers are produced in a cluster at the ends of the stems; seeds are tiny and oblong.

This species has also been known by the scientific name Polygala arenicola.

Habitat

The pine rockland area along the South Florida Limestone Ridge, where tiny polygala is found, is about 65 mi (105 km) long, extending more or less continuously from southeastern Broward County to Long Pine Key in Everglades National Park. The slight elevation of the ridge produces a habitat significantly different from the marshes and wet prairies that dominate the region. The substrate consists of porous limestone known as Miami oolite. Soils are poorly developed, consisting mainly of a thin layer of sand. Erosion of the limestone results in frequent sinkholes and jagged surface features, and many plants are rooted in limestone crevices.

The predominant canopy vegetation on the ridge is southern slash pine. An understory of saw palmetto, silver palm, poisonwood, rough velvetseed, and wax myrtle is typical. Without fire at 3-10 year intervals, the pine-rockland community continues to develop into rockland hammock (hardwoods), which is characterized by oaks, gumbo-limbo, strangler fig, poisonwood, and wild tamarind.

Both populations of tiny polygala are located in open, exposed sand pockets in calcareous rocky pines with a sparse canopy.

Distribution

The plant originally grew in the pine rockland habitat of Broward and Dade Counties, Florida, but attempts to locate this species in Broward County in 1979 were unsuccessful.

Tiny polygala is now known only from two small tracts of remnant pine rockland in the Cutler Ridge area of Dade County. In 1989, fewer than 50 plants were estimated to survive at these sites.

Threats

Because it is higher ground, pine rockland habitat has been extensively developed for residential subdivisions. The historic area of pinelands and hammocks in Dade County, exclusive of Everglades National Park, was once nearly 152,000 acres (61,515 hectares). By 1978, the expanding environs of metropolitan Miami had reduced that figure to about 4,500 acres (1,820 hectares) of pinelands, only about a third of which remained in pristine condition. Since then, the habitat has been further fragmented. Remnant habitat has been degraded by natural plant succession and by the invasion of exotic plants.

Conservation and Recovery

The high cost of land in Dade County has discouraged state or private efforts to acquire parcels of habitat. Without protected sites that can be properly managed, the tiny polygala may not survive in the wild. The U.S. Fish and Wildlife Service (FWS) hopes that some control on development can be negotiated by easements and permits. Florida Power and Light has agreed to cooperate in managing lands in the power line right-of-way areas so as to protect tiny polygala.

Habitat maintenance to control invasion species, as well as restricted burning will assist tiny polygala's recovery. FWS also recommends transplanting some wild individuals to safer habitat, and to establish a seed bank and captive propagation nursery.