Overview
Texas golden gladecress (Leavenworthia texana) is an annual plant and a member of the mustard family, known as Brassicaceae. The genus Leavenworthia includes only eight species in total, all of which occur in glade or prairie/savanna communities. The Texas golden gladecress is an extremely narrow endemic, found in open canopies across the Weches geologic formations of East Texas.
The majority of Texas golden gladecress populations, along with additional areas of suitable habitat, are located on private lands. The bet365下载ios is actively engaged with partners from the Texas Parks and Wildlife Department, universities, and other partners like Mercer Arboretum, Botanical Research Institute of Texas, and The Nature Conservancy to engage in landowner outreach.
The Weches geologic formations are characterized by the presence of the mineral glauconite, and iron becomes concentrated in some of these areas, making them a focus for mining activities. Activities that disturb the soils and geology could affect the Texas golden gladecress, along with additional stressors, including habitat loss, modification and degradation from the invasion of nonnative and native species, pipelines, water lines, and other linear construction projects, glauconite mining and grazing. Effects from a changing climate, small population size and management strategies can negatively impact the viability of the Texas golden gladecress.
Characteristics
Habitat
The Texas golden gladecress grows atop the Weches glades, which are relatively bare, treeless areas with shallow, rocky soils. The plant depends on cool, wet weather that causes pooling and ponding in the glades. Its habitat undergoes a significant seasonal shift. In the spring, the glades are saturated with ponds and pooling soils, while in the summer, the soils become hard and dry.
Physical Characteristics
The Texas golden gladecress is a small, weakly rooted winter annual with glabrous (smooth, glossy) leaves and stems. Its small stature makes it difficult to find except when it is flowering or bearing fruit.
The plant is less than four inches (10 centimeters) in height. The leaves are half an inch to three inches long (2 to 8 centimeters) and about half an inch wide (1 to 1.5 centimeters), growing in rosettes at the base. Its leaf tips are wider than long and are usually distinctly rounded and lobed, with angular teeth.
The plant鈥檚 flowers can occur in several-flowered, short-stalked clusters. Later in the season, the flowers appear on unbranched flower clusters that come off a single central stem, from which the individual flowers grow on small stalks at intervals.
The flowers of the Texas golden gladecress consist of four small petals that are bright yellow with slightly darker bases.
Life Cycle
Texas golden gladecress is part of the ephemeral wetland plant community found seasonally on Weches outcrops. The plant emerges in early winter during cool and extremely wet conditions. In late winter, its flowers bloom, and by early spring, its seeds disperse. Flowers close in the late afternoon on normally sunny days, and they do not open at all on cloudy or rainy days. Each summer, warming temperatures dry out these glades, and the Texas golden gladecress withers away.
The Texas golden gladecress is an annual. Its seeds germinate during spring rains and die back when temperatures warm in summer.
The Texas golden gladecress can reproduce via self-fertilization and by out-crossing with other individuals. Even when self-fertilized, fertilization may still require pollinators. Although specific pollinators of the Texas golden gladecress have not been identified, potential pollinators may include species from the orders Diptera (true flies) and Hymenoptera (ants, bees, and wasps).
The plant鈥檚 fruit splits open explosively and disperses seeds within an extremely limited range of the parent plant, about six to eight inches (15 to 20 centimeters). This is a feature common among most other members of the Leavenworthia genus. When the glade is wet and ponded, the plant is either blooming or fruiting, and moisture may aid seed dispersal within a small glade community but does not provide the connection between more distant population occurrences.
Similar Species
The genus Leavenworthia is endemic to the United States and includes only eight species. Distinguishing these species from one another can be difficult without mature fruit, as five of the eight species have minor differences that can make identification difficult.
Geography
The Texas golden gladecress is found in open canopies across the Weches geologic formations of East Texas, specifically in San Augustine and Sabine counties. An introduced site in Nacogdoches County brings the known extant population count to four.
Timeline
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