|Listed||November 22, 1999|
|Description||A herbaceous, perennial plant.|
|Habitat||Dry, upland terraces above the floodplain of the Rio Grande.|
|Threats||Habitat destruction through agricultural practices and urban development.|
The Zapata bladderpod is a perennial, herbaceous plant. It has sprawling stems 17-34 in (43-85 cm) long and growing from a taproot. Its foliage and stems are silvery-hairy. The basal leaves are 1.5-4.8 in (4-12 cm) long and 0.3-0.6 in (7-15 mm) wide, and have entire to slightly toothed margins. The stem leaves are 1.0-1.5 in (3-4 cm) long and 0.1-0.3 in (2-8 mm) wide. The inflorescence (grouping of flowers) is a loose raceme of bright, yellow-petalled flowers, which are arranged along an axis with the lower flowers maturing first. Its ripe fruits are round, 0.2-0.8 in (4.5-6.5 mm) in diameter, and borne on short, downward curving stems (or pedicels).
The Zapata bladderpod occurs on gravelly to sandy-loam upland terraces above the floodplain of the Rio Grande. Its habitat is subject to severe and unpredictable drought. The Zapata bladderpod occurs as a herbaceous component of an open cenizo (Leucophyllum frutescens ) shrub community that grades into a blackbrush (Acacia rigidula ) shrub community.
The Zapata bladderpod is a local (or endemic) species that only occurs in Starr and Zapata Counties, in south Texas.
The Zapata bladderpod is threatened by over-grazing by livestock, conversion of its habitat into seeded pasture, residential development, and invasion of its habitat by non-native plants, especially the buffelgrass (Cenchrus ciliaria ) and Kleberg's bluestem (Dichanthium annulatum ). Road construction and other activities associated with oil and gas development are also a threat. These types of activities have destroyed or altered more than 95% of the native habitat in south Texas. Ten sites of the Zapata bladderpod are known, but at least four of these populations are extirpated. Only four sites were definitely known to support populations in the late 1990s.
Conservation and Recovery
One site supporting the Zapata bladderpod occurs in the Lower Rio Grande Valley National Wildlife Refuge complex. Another site beside a highway is being conserved under a management agreement with the Texas Department of Transportation. The largest populations on private land must be protected. This could be done by acquiring the land and designating ecological reserves, or by negotiating conservation easements with the private landowners. The known populations of the endangered Zapata bladderpod should be monitored, others searched for, and research undertaken into its biology and habitat needs.
U. S. Fish and Wildlife Service, Ecological Services Field Office
c/o Texas A&M University-Corpus Christi
Campus, 6300 Ocean Drive
Campus Box 338 Corpus
Christi, Texas 78412-5599
Telephone: (316) 994-9005
Fax: (361) 888-3189
U. S. Fish and Wildlife Service. 22 November 1999. "Endangered and Threatened Wildlife and Plants: Determination of Endangered Status for the Plant Lesquerella thamnophila (Zapata Bladderpod). Federal Register 64 (224):63745-63752.