Physiognomy and Structure: No Data Available

Floristics: This is an edaphically controlled grass-forb association. One zone consists of "slick spots," areas denuded of vegetation which are rimmed by a "cryptogamic lip" of lichens, algae and diminutive vascular plants. Geocarpon minimum occurs in this zone in the West Gulf Coastal Plain. Farther back from this lip, Cladonia lichens, Aristida longespica, Aristida purpurascens, Aristida oligantha, and Schizachyrium scoparium sequentially become dominant, along with Sabal minor in the West Gulf Coastal Plain. Diodia teres is also characteristic. Krigia occidentalis and Ambrosia artemisiifolia may be present. Schoenolirion wrightii is a regionally rare species in this zone.

Dynamics:  The topsoil is thin silt with toxic levels of sodium and/or magnesium salts in the subsoil, and is some areas are often exposed as "slick spots," which are denuded of vegetation. Although the subsoil is silt, it is essentially cemented into an impervious hardpan by calcium or other minerals. Sites therefore alternate between extremely dry and extremely wet, a condition that has been described as xerohydric. Genesis is uncertain, but salts may be "wicked" to the surface through evaporation. The role of fire in maintaining this community is not understood; some areas may support relatively frequent fire, and others are too thinly vegetated to carry a fire. The "slicks" appear to be somewhat ephemeral features, appearing, disappearing, and migrating over time at a site. "Not only did the Geocarpon disappear from the transects, but many of the slicks themselves disappeared. First they were encroached by lichen, then by Aristida, Ambrosia bidentata, and mosses... some of them are no longer even discernible as having been slicks in the past" (T. Witsell pers. comm.). "In an effort to monitor Geocarpon populations over time, experimental transects were set up in saline prairie areas. The project was a miserable failure because the plants disappeared from the transects. Then someone noticed that there were unrecorded, apparently new, slicks nearby that had Geocarpon. A comparison of old and new aerial photos should show the change in location of slicks" (T. Foti pers. comm.).