White Bladderpod

Lesquerella pallida

Description

White bladderpod, Lesquerella pallida, is an annual with unbranched or slightly branching stems that grow between 2-23 in (5-60 cm) tall. Individual plants occasionally spread to form bushy clumps. Going up the plant, the simple leaves decrease in size and number. Plants produce white, four-petal flowers with yellow bases; some have been observed with as many as 24 flowers. The species gets its common name from the bladder-shaped fruit.

Habitat

White bladderpod occurs on the gently rolling coastal plain of eastern Texas associated with oak-hickory-pine woodland vegetation. It is found in glades or pastures where calcareous rock of the Weches Formation protrudes. These rocky outcrops are underlain by an impermeable barrier of glauconite (a silicate) that keeps the ground seepy and wet for much of the year.

Distribution

The extent of its historic range is unknown, but the plant is probably endemic to eastern Texas. A total of eight populations occupying less than 30 acres were known, as of 1994, on private land and a county road right-of-way in San Augustine County. White bladderpod was first collected near San Augustine, Texas, in the 1830s but was not re-discovered until 1981.

Two additional populations were discovered in 1985, one of which had 200 plants in 1990 but only 10 in 1992. In 1988, two more populations were found, the larger of which, in a lightly grazed pasture, contained more than 1,000 plants in 1988. Its number briefly soared to a high of 4,000 plants in 1991 before declining precipitously to a low of 200 plants in 1992. The other 1988 population discovery boasted 1,000 plants that year, but had none visible in 1990 and only eight in evidence the following year.

Another population was found in 1991, in an improved pasture approximately a mile south-south-east of San Augustine; a small population, it had only three plants in 1991 and none in 1992. The absence of plants from one year to the next, however, does not necessarily mean the species has been extirpated from that spot.

Two additional populations were discovered in 1994 through efforts supported by the Fish and Wildlife Service, Clear Lake, Texas, Field Office. All other known historic locations were visited to determine if the species is still present. Specimens were found at all sites, but in limited numbers in most locations due to invasions of exotic plants.

Threats

The plant's populations occur on moderately grazed pastureland and are susceptible to damage from livestock and pasture management techniques, such as herbicide application. If grazing were intensified, populations would be seriously jeopardized. The two smaller sites appear to be succumbing to later stages of vegetational succession. Woody and shrubby species, such as the Macartney rose, blackberry, and sumac, are encroaching on white bladderpod sites and will eventually crowd out the plant if left unmanaged. One site is threatened by road maintenance and by trash dumping.

Conservation and Recovery

In 1996, the Fish and Wildlife Service (FWS) Clear Lake, Texas, Field Office secured funding and landowner cooperation to selectively clear invasive shrubs from 20 acres (8 hectares) of historic and current habitat of the white bladderpod and a listing candidate, the Texas golden gladecress (Leavenworthia texana ). Previously damaged by road construction and overgrazing, the primary threat to the habitat is extensive encroachment by non-native shrubs. Besides manual clearing of the exotic plants, the FWS has worked with the state's Department of Agriculture to develop reasonable restrictions on the use of a herbicide commonly applied by area landowners. The effort involved more fully identifying the areas of concern, and developing time of usage and application alternatives that would allow landowners to control shrub encroachment without jeopardizing the rare native species.

Contact

Regional Office of Endangered Species
U.S. Fish and Wildlife Service
P.O. Box 1306
Albuquerque, New Mexico 87103
http://southwest.fws.gov/

References

Mahler, W. F. 1985. "Status Report Update, Lesquerella pallida, Spring 1985." U.S. Fish and Wildlife Service, Albuquerque.

Nixon, E. S., J. R. Ward, and B. L. Lipscomb. 1983."Rediscovery of Lesquerella pallida (Cruciferae)." Sida 10:167-175.

Rollins, R. C. and E. A. Shaw. 1973. The Genus Lesquerella (Cruciferae) in North America. Harvard University Press, Cambridge.

U.S. Fish and Wildlife Service. 1987. "Endangered and Threatened Species of Texas and Oklahoma (with 1988 Addendum)." U.S. Fish and Wildlife Service, Albuquerque.

U.S. Fish and Wildlife Service. 1992. "White Bladderpod Recovery Plan." U.S. Fish and Wildlife Service, Albuquerque.