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Geocarpon
Geocarpon minimum
Family: Caryophyllaceae
Description: A very small, succulent annual that ranges from 0.4-1.6 inches (1-4 centimeters in height). The flowers lack petals and are inconspicuous in the axils of the leaves. The leaves are sessile and oppositely arranged on the stems. The young plants are a dull gray color and turn reddish-purple upon maturity. The life cycle of Geocarpon begins in early spring and lasts for only three weeks.
| Status: |
Federally Listed Threatened (June 16, 1987) Global Rank: G2 State Rank: S2 |
Distribution: Populations of this species occur in Arkansas, Louisiana, and Missouri. Geocarpon occurrences in Arkansas are limited to Bradley, Drew, and Franklin Counties.
Habitat: In Arkansas, Geocarpon is restricted to a very rare habitat known as saline soil barrens. These savanna- or prairie-like openings are the result of high concentrations of sodium and magnesium in the soil, and are found in only a few places in the West Gulf Coastal Plain and Arkansas Valley (Warren Prairie Natural Area). Within these barrens, Geocarpon is typically found along the margins of localized areas of bare mineral soil known as "slicks." These slicks are outcrops of a very salty subsoil layer and are characterized by the presence of iron nodules, high root toxicity, low organic matter, and poor aeration. Slicks change over time, migrating over a localized area, and Geocarpon subpopulations must move with them. As a result, this species is highly vulnerable to local extirpation if suitable habitat is not protected.
Conservation Status: Geocarpon has probably always been rare in Arkansas due to its dependence upon a rare habitat type. However, this habitat has been made scarcer through changes in land use. Soil disturbance caused by vehicles, log-loading operations, timber site preparation, and conversion of suitable habitat to cattle grazing, have the potential to affect Geocarpon microhabitats by altering the condition and quality of slicks. Proper management and protection of the areas Geocarpon currently inhabits is critical as extirpated populations seldom reestablish and the potential for this species to recolonize areas of suitable habitat is poor.
