Large-fruited Sand-verbena

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Large-fruited Sand-verbena

Abronia macrocarpa

Status	Endangered
Listed	September 28, 1988
Family	Nyctaginaceae (Four-o'clock)
Description	Herb with erect stems, alternate hairy leaves with sticky glands, and spherical clusters of pink-purple flowers.
Habitat	Deep, blowing sand dunes.
Threats	Low numbers, limited distribution, habitat disturbance.
Range	Texas

Description

Large-fruited sand-verbena, Abronia macrocarpa, is an herb that grows in ascending, erect stems to a height of 20 in (50 cm). Hairy leaves with sticky glands are arranged alternately along each stem. In spring, attractive, nodding spherical flower clusters the size of a tennis ball form at the ends of the stems. The clusters consist of 20-75 pink-purple flowers. Large papery fruits form by summer. Seeds are dispersed by the wind.

Habitat

This species is one of the first plants to take root in the tracts of sandy dunes that occur within a larger mosaic of oak woodlots and grasslands. The dominant plants are post oak and yaupon, which form wooded enclaves among the dunes. Sand-verbena temporarily dominates the bare sandy surfaces when blooming in the spring.

Distribution

The large-fruited sand-verbena is endemic to localized sand dunes in central-eastern Texas. The full extent of the historic range is unknown. It is known to occur at only three sites in east-central Texas, where fewer than 3,000 individuals are known to survive. One population of large-fruited sand-verbena is known from a dune region of about 30 acres (12 hectares) in Leon County, Texas (situated nearly halfway between Dallas and Houston). In 1986, the population consisted of about 250 plants scattered across the site. This dune habitat is part of a resort community that supports many recreational pastimes including bicycling, horseback riding, and off-road vehicle use. This traffic has cut wide swaths through the dunes, disturbing the sand so that plants cannot become established.

Threats

Residential and resort development has moved into Leon County from both north and south, swallowing up tracts of sandy habitat that once supported the sand-verbena. New feeder roads, built to allow access to residential subdivisions, are certain to stimulate further development in remaining sand-verbena habitat.

Conservation and Recovery

Because the population is on private land, it was determined that no added benefit would accrue to the plant from a declaration of Critical Habitat. The U. S. Fish and Wildlife Service (FWS) is attempting to negotiate at least a temporary conservation management plan with the landowners that would buy time to transplant or establish the sand-verbena to other more protected sites. Protection of the population requires fencing to prevent disturbance of plants. With landowner cooperation, the large-fruited sand-verbena may survive long enough to allow botanists to establish new, more secure populations.

According to the 1992 FWS Recovery Plan for the species, the large-fruited sand-verbena will be considered recovered when at least 20 demographically stable, genetically viable populations—each comprised of at least 600 plants and covering at least 25 acres (10 hectares)—have flourished for 10 years or more.