A surge in the collection of exotic Marsilea, M. mutica, M. minuta and M. hirsuta in the southeastern United States has prompted the need for updated identification aids. This study provides an annotated key to all water-clover ferns occurring in the region. It describes and illustrates recently documented exotic species and a previously misidentified western introduction. It details the rediscovery of M. ancylopoda, presumed extinct, and confirms its identification as the western species M. oligospora. Finally it clarifies the status and distribution of two additional western North American species introduced to the southeast, M. vestita and M. macropoda.

Isoetes melanopoda, a diploid species of ephemeral prairie wetland swales primarily in central North America, has also been found in swamp forests over a wide area of eastern North America in recent years. Determination of certain morphological and ecological characteristics (leaf width, habitat preference, leaf base color, megaspore ornamentation pattern, and megaspore size) distinguishes two population groupings within the species range that maintain discreet geographic distributions and thus represent distinct taxa. Most populations of these two eastern and western taxa are distinctive enough to argue for identification as separate species within I. melanopoda (s.l.). The existence of some apparently intermediate populations within a transition zone between the two taxa and the absence of stand-alone diagnostic identification features, however, indicates that a subspecific level of distinction is more appropriate. Isoetes melanopoda subsp. silvatica, subsp. nov., is proposed for the previously unnamed eastern taxon.

A large population of the globally rare shrub Buckleya distichophylla occurs on Poor Mountain, Roanoke County, Virginia in the Blue Ridge Mountains. Plot data were taken to characterize the forests associated with this rare shrub. Cluster analysis identified three forest types based on overstory composition: mixed hardwoods, Quercus prinus and Pinus pungens. Ordination and discriminant analyses showed that B. distichophylla was associated with xeric sites dominated by P. pungens with a thick layer of ericaceous shrubs. The evidence of past fires and the abundance of fire-intolerant trees, e.g., Nyssa sylvatica, in the understory suggest that the forests are slowly succeeding in the absence of periodic fires. Advance regeneration of P. pungens may not be adequate to perpetuate its current dominance on xeric sites. Buckleya distichophylla is an integral component of the pine-oak/heath woodland natural community on Poor Mountain and may be more of a fire-adapted species than previously thought.

Carex roanensis is a globally rare species endemic in moderate to high elevation forests in the southern Appalachian Mountains. All known collections were reviewed, including previously unpublished records from Pennsylvania, West Virginia, Virginia, North Carolina, and Tennessee, and an annotated distribution map is presented. A preliminary assessment of its ecological affinities is provided, especially with respect to the closely related C. aestivalis and C. virescens.

The vascular flora was studied and plant habitats described within an abandoned limestone quarry contiguous to Center Hill Dam in DeKalb County, central Tennessee, between 1986–2000. From seven diverse quarry habitats, 282 species in 203 genera and 81 families were documented. One hundred sixty-two species (57.4%) are DeKalb County distribution records. Sixty-four (22.7%) are exotic taxa including 22 Tennessee “severe threat” and “significant threat” invasive exotic pests. The known vascular flora includes five Pteridophytes, three Gymnosperms, and 273 Angiosperms (69 Monocots, 205 Dicots). Two state-listed species were discovered: Elymus svensonii and Liparis loeselii. Carex molesta is reported here as a new addition to the Tennessee flora.

A two-year floristic survey of the 7,690-ha Pushmataha Wildlife Management Area (PWMA) located in the Kiamichi Mountains of southeastern Oklahoma revealed the known vascular flora to comprise 447 species in 287 genera and 97 families. The four largest families—Poaceae, Asteraceae, Fabaceae, and Cyperaceae—compose 43.4% of the flora. The largest genera are Carex, Juncus, Dichanthelium, Desmodium, and Lespedeza. Native species account for 92.8% of the taxa. Three introduced species appear to be naturalizing in the area: Elaeagnus angustifolia, Lespedeza cuneata, and Sorghum halepense. Thirteen species designated as rare by the Oklahoma Natural Heritage Inventory were encountered: Dulichium arundinaceum, Justicia ovata var. lanceolata, Brachyelytrum erectum, Calamovilfa arcuata, Piptochaetium avenaceum, Smilax smallii, Ilex opaca, Ribes cynosbati, Tilia americana var. caroliniana, Polygala polygama, Carex oxylepis, Carex oklahomensis, and Mitchella repens.