|Listed||January 8, 1987|
|Description||Annual with hairy stems and leaves and yellow flowers.|
|Habitat||Open glades in shallow, limestone soils.|
|Threats||Habitat disturbance, collectors.|
Missouri bladderpod (Lesquerella filiformis ) is a winter annual with numerous erect, hairy stems that are about 8 in (20.3 cm) in height. Silvery leaves are hairy above and beneath. Basal leaves are spatula-shaped and attached by a narrow petiole or leaf-stalk; leaves toward the tops of the stems are narrower and lacking in petioles.
Light yellow flowers with four petals appear at the tops of the stems in late April or early May. As the green seed capsule develops and matures, it turns tan, splits open, and disperses seeds (usually within four weeks after flowering), leaving a papery partition (septum) attached to the flower stalk. Stems die back, and the plant overwinters as a basal rosette. The scattered seeds germinate in the fall and remain dormant throughout the winter. Seedlings sprout, flower, and bear fruit as temperatures and rainfall increase in the spring.
An unusual growth pattern for this plant has been observed in populations found on the highway rights-of-way. Stands of the plant are seen for one or two seasons, disappear completely the next year, then reappear the following year.
Missouri bladderpod is found in open limestone glades where soils are shallow and where the limestone bedrock lies near the surface. These localized conditions occur within the prairie region of southwest Missouri.
Plants frequently associated with Missouri bladderpod are wild hyacinth, false garlic, prickly pear, savory, a spiderwort (Tradescantia tharpii ), a vervian (Verbena canadensis ), and a species of Sedum. Missouri bladderpod is usually not dominant within the community.
The historic range of the Missouri bladderpod includes five Missouri counties between Springfield and Joplin-Greene, Dade, Christian, Jasper, and Lawrence counties.
The plant can be found at nine scattered sites within its historic range. The low number of plants (estimated at fewer than 5,000 in 1986) and the few remaining sites make the species vulnerable to collecting and other human disturbance. Populations in Jasper and Lawrence counties appear to have died out.
Three of the nine remaining populations are on Missouri state highway rights-of-way and are periodically mowed during routine maintenance. Four populations are on private land with no protection; two are found within the Wilson's Creek National Battlefield Park.
The species is listed as occurring in Arkansas and Missouri by the U. S. Fish and Wildlife Service.
In 1984 more than 124,000 people visited Wilson's Creek National Battlefield Park. By the 1990s that number had increased fourfold, putting additional stress on the area's vegetation. The battlefield is crisscrossed by interpretive trails for visitors, who occasionally intrude upon the two populations accessible from the pathways. Wildflower collectors sometimes pick the flowers or dig up the more accessible plants for their gardens, but collected plants soon die.
Insects feed upon the plant's seeds and a type of fungus has been know to infest developing seed capsules. Both factors reduce the plant's reproductive capacity and may pose a significant threat to its survival.
Conservation and Recovery
To help in its recovery, the Missouri Botanical Garden is prepared to bring Missouri bladderpod into protective cultivation under the auspices of the Center for Plant Conservation. A secure population occurs at Greenfield Glade, where the Nature Conservancy owns a preserve.
Morgan, S. W. 1983. " Lesquerella filiformis : An Endemic Mustard." Natural Areas Journal 3: 59-62.
Morgan, S. W. 1986. "A Study of a Population of Lesquerella filiformis Rollins in Missouri." Report. Missouri Department of Conservation, Jefferson City.
U. S. Fish and Wildlife Service. 1988. " Lesquerella filiformis Recovery Plan." U. S. Fish and Wildlife Service, Twin Cities.