STATUS ASSESSMENT OF ELEOCHARIS WOLFII (CYPERACEAE) IN THE UNITED STATES

Eleocharis wolfii (Wolf's spike-rush) is listed by NatureServe as G3G4 and as S1 (critically imperiled), S2 (imperiled), SNR/SU (not ranked or currently under review), or SH (historical) in most states where the species has been documented. Recent field studies in Arkansas, Illinois, Kansas, Louisiana, Missouri, and Nebraska suggest that the species is not as rare as previously believed but simply overlooked. Pre-1978, the species was known from 59 sites in 43 counties/parishes in 17 states and possibly two others. Post-1978, Wolf's spike-rush has been documented at 222 sites from 104 counties/parishes scattered across 16 states. Since 2000, 135 new sites distributed among 64 counties/parishes in 15 states have been discovered. Eleocharis wolfii is easily recognized in the field by the combination of tiny rhizomes; purple-red culm bases; blue-green, flattened and spirally twisted culms; and mostly white achenes < 1.0 mm long with 9-19 longitudinal ridges and 30-60 transverse trabeculae. The species is known from a wide variety of habitats including wet depressions of bottomland and mesic upland prairies, ephemeral pools in open grasslands, limestone and saline barrens, and ephemeral pools or shallow depressions on sandstone, granite, or quartzite outcrops. Eleocharis wolfii may be found in nearly pure monoculture stands but is often found with a wide variety of plant associates depending on soil and natural community type. Significant threats to Eleocharis woljii habitat persist over much of its range and include the cutting of many bottomland forests; habitat destruction due to residential and commercial development; the conversion of native prairie to agricultural crops, pasture or hayfields; and the loss of wetlands. There are insufficient regulatory mechanisms in place in most states to provide any protection for the species. The potential impact of projected climate change on E. woljii is unknown. Planned increases in ethanol production in the Midwest may negatively affect the species. Additional surveys are needed in the Midwest, the Great Plains states, and states bordering or adjacent to the Great Lakes. The species would benefit from additional research including studies on life history and ecology; seed viability; population genetics; germination requirements; inter-specific competition; land use changes; and the potential impacts of invasive species. Management actions that may benefit Wolf's spike-rush include prescribed fire, haying or mowing