Saxifraga tridactylites (Saxifragaceae), an annual herb native to northwest Africa, southwestern Asia, Europe, northeastern Iran, and western Russia, has rapidly naturalized in two geographically distinct areas of the United States: the Southeast and the Northwest. In the Southeast, the spread has been exceedingly fast and poses a potential threat to xeric limestone habitats of the Interior Low Plateau and Ridge and Valley physiographic provinces. Prior to our work, S. tridactylites appeared to be an insignificant introduction, only documented in a few North American locations in British Columbia and Oregon. Here, we show that the North American distribution is much greater than previously reported, with records from four counties in the Northwest and 53 counties in the Southeast: northern Alabama (14 counties), northwest Georgia (two counties) northern Mississippi (five counties), and southern Tennessee (32 counties). To our knowledge, it has not yet dispersed into Arkansas, Kentucky, or North Carolina.

Fifty-seven county records, representing 56 species and 28 vascular plant families, are reported here as new additions to the Virginia flora. All voucher specimen are housed in the Radford University Herbarium (RUHV). Our study examined the entirety of the nearly 10,000-specimen collection at Radford University. Each specimen was manually cross-referenced with current county records; when potentially new county records were discovered, identifications were verified. We also determined whether any new county records were listed as state-, federally-, or globally-imperiled. Among the county records, we also determined the number and distribution of non-native and potentially invasive species. Most specimens were collected from Virginia's Appalachian Mountain region. Of the 56 species, two have conservation ratings of globally and state “vulnerable” (Monotropsis odorata and Aconitum reclinatum). Several others are “globally secure” but of concern in Virginia, including two state-imperiled species (Calopogon tuberosus and Stylophorum diphyllum) and three vulnerable species (Carex shortiana, Pogonia ophioglossoides, and Stachys latidens). We also document the first county records of three invasive species (Ludwigia grandiflora ssp. hexapetala, Poa trivialis, and Securigeria varia). These contributions show how smaller herbarium collections contribute to our understanding of Virginia's natural history and native and non-native flora.

Table Mountain pine (Pinus pungens) is an Appalachian endemic that requires canopy-opening disturbance such as fire or logging for successful regeneration. The infrequency and typically moderate intensity of Appalachian lightning-ignited fires combined with Table Mountain pine's requirement for canopy disturbance for successful recruitment posed an ecological question: How did Table Mountain pine (TMP) persist in North America for almost 1.5 million years without anthropogenic fires? An early monograph on TMP suggested that the species might have persisted without fire on extremely xeric and sterile rock outcrops. Motivated by this suggestion, in 1976 the first author located a small TMP population on a xeric rock outcrop in western North Carolina where no fires had occurred since 1889. Three longitudinal censuses in 1976, 1986, and 1996 showed that the population had perpetuated itself without fire for more than 100 years. The current study extends this record of self-maintenance an additional 20 years and compares decadal variations in age structure with 120 years of drought records from western North Carolina. An unexpected observation of this 40-year study was a slow invasion of the TMP study site by ericaceous shrubs, a terminal transition that was predicted in a 2010 model of oak-pine-heath succession without fire.

Despite the ecological and economic importance of pines (Pinus) in the southeastern United States, there exist no taxonomic keys or resources that facilitate the comprehensive identification of pine seedlings. The objectives of this study were to analyze select aspects of seedling morphology for the three primary pines associated with Piedmont upland grassland systems of conservation concern (Pinus echinata, P. taeda, and P. virginiana) and subsequently to develop a resource, traditional or probabilistic, depending on the outcome, to facilitate species-level determination. Two characters—the number of primary needles in the first whorl post-germination and needle apical curvature relative to the stem—were assessed through analysis of 3,200 seedlings under field conditions. The mean number of primary needles in the first whorl was 5.9 (s.d.=0.56) for P. echinata, 7.3 (s.d.= 0.79) for P. taeda, and 5.3 (s.d.=0.63) for P. virginiana. Predominant needle apical curvature was away from the stem in P. echinata (90.5%) and P. virginiana (91.5%), but toward the stem in P. taeda (97.5%). Based on these data, a probabilistic diagnostic framework that takes into consideration both morphology and stand composition is presented, including supplemental appendices of calculated posterior probabilities.

A floristic survey and analysis of community composition were conducted at the Blue Ridge Center for Environmental Stewardship (BRCES) in Loudoun County, Virginia during 2017 and 2018. BRCES comprises 392 hectares of open and forested upland and wetland habitat between the Blue Ridge and Short Hill Mountain in the Northern Blue Ridge physiographic province. In 2014, the majority of BRCES was transferred to the Virginia Department of Conservation and Recreation to be developed into the county's first state park. This study provides the first comprehensive inventory of its vascular flora. In total, 515 vascular plant species belonging to 328 genera and 105 families were identified. Forty-four species and seven varieties and subspecies identified were new records for Loudoun County. Pycnanthemum torreyi and Platanthera peramoena, which are considered rare at the state level under the Virginia Natural Heritage Resources designations S2 (imperiled) and S1 (critically imperiled), were recorded. Eleven 20 m × 20 m forest vegetation plots were used to determine community types as defined by the Virginia Natural Heritage Program. Forested habitat comprised five distinct community types belonging to terrestrial and palustrine systems: Inner Piedmont/Lower Blue Ridge Basic Oak-Hickory Forest, Piedmont/Central Appalachian Rich Floodplain Forest, Northern Piedmont Small-Stream Floodplain Forest, Inner Piedmont/Lower Blue Ridge Basic Mesic Forest, and Piedmont/Central Appalachian Mixed Oak/Heath Forest.

The vascular flora of Butler County, Alabama, was surveyed from 1985 to 2019. A total of 1,524 species, hybrids, or subspecific taxa in 654 genera from 170 families are reported. Fifty-seven species represented by herbarium specimens from Butler County were not re-collected during this study. The Inventory List of Rare, Threatened and Endangered Plants, Animals and Natural Communities of Alabama as compiled by the Alabama Natural Heritage Program contains 36 of the species collected. Approximately 20% of the flora (310 species), are considered non-indigenous. Families with the largest number of species, hybrids, or subspecific taxa were Asteraceae (205), Poaceae (179), Fabaceae (103), Cyperaceae (92), Rosaceae (53) and Lamiaceae (36).

Intraspecific phenotypic variation occurs for many different reasons and understanding its basis has applications in taxonomy, ecology, and evolution. Chamaecrista fasciculata (partridge pea) is a widely distributed species with much phenotypic variation and varied interactions with other species in communities where it grows. Botanists have often noted that phenotypic variation in some traits of this species increases from north to south in the eastern United States. In this study, we grew seeds collected from five Mississippi populations in a common greenhouse environment to determine if the observed variation in leaf and stem traits is maintained in this environment. Interpopulation variation in the greenhouse-grown plants was not as extensive as that observed under natural conditions, but significant differences were detected in the number of stems and leaves and shoot height. The number of flowers and final shoot weight of plants did not differ, suggesting that there may be multiple growth strategies for this species to achieve equal fitness. Variation was detected in stem and leaflet trichome density. The population collected at the lowest latitude showed the most distinct morphology, producing shorter plants with many branched stems, more leaves, and a higher degree of leaflet pubescence. Trait variation that has so often been observed in natural populations of this species is maintained in a common environment, suggesting a genetic basis for the observed variation. Phenotypic variation observed in this species may reflect both responses to varied selective pressures from interacting species and adaptation to differing climatic factors.

We assessed population genetic structure and rate of hybridization in Sarracenia flava and S. minor in Francis Marion National Forest. The forest has an abundance of potential habitat for our study species and has suffered less human mediated disturbance than much of the county's longleaf pine savanna and wet pine savanna ecosystems. We examined 63 S. flava and 62 S. minor individuals, as well as one hybrid across a 486.02 km² study site. We used eight nuclear microsatellite loci and one non-coding chloroplast marker to assess population genetic structure and describe the parentage of the hybrid. We found relatively little population genetic structure across many distinct field sites, even when those sites were separated by unsuitable habitat. In very small populations surviving in shrub-dominated longleaf pine savanna, genetic divergence was greater than in larger populations with more suitable habitat. The single hybrid discovered was an F₁ hybrid for which S. flava served as the maternal parent. We found no signs of introgression. We hope that these data can help inform conservation decisions regarding Sarracenia species, as the low genetic structure seems to suggest a high degree of connectivity between geographically distinct populations of plants.

Periphyton and water were sampled 1 km upstream of the Cookeville Wastewater Treatment Plant (PR_upstream), 2 km downstream of the discharge (PR_downstream), and from a tributary (PO) 10 km south of the wastewater treatment plant. Percent composition of 113 algal taxa were documented. Assemblages of soft-bodied algae and diatoms at the PR_downstream site had more eutrophic taxa than assemblages at the other sites. Water at the PR_downstream site had >7-fold higher concentration of total phosphorus (193 µg·L^-1), yet <1.5-fold higher concentration of total nitrogen (1900 µg·L^-1) than water at the other sites. The total nitrogen to total phosphorous ratio (TN:TP ratio) at the PR_downstream site (9.8) was below the value hypothesized for N-limitation of algae growth (10), whereas the ratios at the PR_upstream site (65.9) and PO site (62.4) were above. Phosphorus and nitrogen additions to in vitro growth assays using Raphidocelis subcapitata indicate in vitro carrying capacity for Raphidocelis subcapitata was P limited in water from the PR_upstream and PO sites. In vitro carrying capacity for Raphidocelis subcapitata was significantly greater and N-limited in water from the PR_downstream site. The results indicate that reduction of the TN:TP ratio of Pigeon Roost Creek changed the nutrient that limits in vitro carrying capacity for R. subcapitata from P to N, and imply that standard growth assays using Raphidocelis subcapitata to evaluate carrying capacity of P-enriched stream water may not indicate the extent of the impact of the P-enrichment to a watershed due to N-limitation of carrying capacity in vitro.

Three species of vascular plants and one hybrid are reported here as new to Alabama: (Lycopodium clavatum, Pterocaulon virgatum, Chrysopsis lanuginosa, and Asimina ×piedmontana). The Pterocaulon virgatum records represent the first collections of this species from east of the Mississippi River. The Chrysopsis lanuginosa record is the first for that species outside of Florida. Based on habitat, population size, and/or previous collections, all of these species are considered to be native to the flora of Alabama.

Mitreola petiolata and M. sessilifolia in the Loganiaceae are similar wetland annuals occurring in tropical, subtropical, and temperate regions in the southeastern U.S., Africa, Asia, and Oceania. The flowers of both species have previously been described to open briefly with an apparent window for outside pollination, followed by flower closure and massive pollen germination within the anthers with pollen tubes covering the adjacent stigma. The phenomenon was documented with field observations, floral dissections, and light and scanning electron microscopy. Both species open their flowers for a brief 6–8 hour window. Subsequently, pollen germinates within the closed or closing flower with pollen tubes completely covering the stigma. The prevalence and importance of selfing by precocious pollen germination are discussed.

Guettarda scabra leaves are consumed by a variety of moth caterpillars, some with adults that visit the flowers and may serve as pollinators. Flower-opening is hastened by eager flower-flies, and during the night the flowers are visited by hawk moths (Sphingidae); in the morning they are visited by butterflies.

Curculio and Conotrachelus weevils (Coleoptera: Curculionidae) can render the majority of North American Quercus spp. acorn crops nonviable, thereby reducing food resources for wildlife and limiting opportunities for seedling establishment. Acorn predation by weevils at the individual tree level can be influenced by many factors, and research specifically investigating acorn predation by weevils in seasonally flooded bottomland oak forests is lacking. We placed cone emergence traps in a periodically flooded forest on the Sam D. Hamilton Noxubee National Wildlife Refuge near Brooksville, Mississippi to obtain weevil population parameter estimates, record emergence phenologies, and identify variables that may aid in understanding tree-to-tree variability in acorn predation rates. Forty-three Curculio weevils representing five species emerged from mid-August through early November, and 56% of those captured emerged over an 11-day period in mid-September. Sixty-four Conotrachelus weevils representing two species emerged from mid-August through late November and occurred at nearly twice the density of Curculio weevils. The exotic Asiatic oak weevil, Crytepistomus castaneus, a minor defoliator, emerged from August through early November. We also identified Quercus density, specifically the proportion of oaks that immediately neighbor the host tree, as a potentially important explanatory variable of acorn predation by weevils at the tree level in bottomland forest habitats.

Initially formed as a Civilian Conservation Corps camp in 1935, Chewacla State Park is a 282 ha property established in 1939. The park is currently managed by the Alabama Department of Conservation and Natural Resources, State Parks Division as a public recreational resource. A floral survey of this area was conducted from August 2014 through May 2019. A total of 704 species (incl. five hybrids) from 415 genera and 137 families were collected in the park. Asteraceae was the largest family with 98 species. Poaceae, Fabaceae, and Cyperaceae were the next largest families with 72, 48, and 48 species, respectively. Carex (Cyperaceae) was the largest genus, represented by 25 species. Seventy species are reported for the first time from Lee County, and one for the state of Alabama. One hundred and thirty-nine (19.7%) non-native species were collected during the surveys. Voucher plant collections made for this study are held at the Alabama Natural Heritage Section Herbarium (ALNHS) and the John D. Freeman Herbarium (AUA) with duplicates sent to the Anniston Museum of Natural History Herbarium (AMAL) and New York Botanical Gardens (NYBG).

Human landscape modification elicits changes in plant community composition due to altered microclimate conditions. We asked the question whether floristic composition, abundance, species richness, and diversity differ between habitat types in two human-modified landscapes, with contrasting management regimes. We measured species richness and cover of all vascular plants in forest, edge, and corridor habitats of a powerline easement, as well as in a nearby old field. Powerline corridor habitat had 21% more species than adjoining forest habitat and was dominated by shrub and herbaceous species. We also found that soil pH and litter depth are significant predictors of species richness along powerline corridor edges and in open old-field habitat. Particularly, we observed maximum species richness in plots with moderately high soil pH of between 5 and 5.5 along powerline corridor edges and in open old-field habitat. Powerline corridor plots with less surface litter also had higher species richness. Invasive species such as Microstegium vimineum and Rosa multiflora were more abundant in the open old-field habitat maintained annually by mowing than in powerline corridor habitat maintained usually every five years by herbicide spraying and selective removal of trees. Our findings indicate that the diverse floristic composition of powerline corridors support organisms at higher trophic levels and hence provide opportunity for conserving biodiversity within human-modified landscapes.

The annual signature of the roots of relatively few species of North American herbaceous perennials is known, which is unfortunate, considering the potential contributions an increased understanding of age structure of populations of such species could represent. To help fill this gap, we briefly communicate here results of recent work on Echinacea laevigata and E. pallida (Asteraceae, Heliantheae), both species of conservation concern in the eastern United States. Analysis of cross-sections of individuals of known age of both species revealed an annual signature consistent with that reported for other herbaceous perennials, namely the development of clusters of vessels with conspicuously large diameters, marking annual spring root growth, followed by vessels of reduced diameter in the remainder of the year.

The Southern Ridge and Valley Calcareous Flatwoods community is represented by a diverse and unique plant association. Atypical edaphic processes may explain the presence of disjunct or nearly endemic species, including several federal/state endangered and rare species. To evaluate this community, we surveyed a 238-ha plot at Berry College (Floyd County, GA) within a known calcareous flatwoods habitat. Contiguous 30 m wide transects were surveyed for 12 focal species in 2018. Canopy photos and soil samples were taken at sites where focal plants were found, as well as at 30 random sites within the plot. Soils were analyzed for pH, lime buffer capacity (LBC), Ca, Mg, P, K, Mn, and Zn. Canopy photos were analyzed for variables related to canopy openness. Of focal species, only Asclepias hirtella (N=52) and Marshallia mohrii (N=12) were found during the survey. Contrary to expectations, this habitat was not uniformly high in Ca (mean 603 ppm) or pH (mean 4.8). Sites where focal species were found differed from random sites in LBC (lower for both species), variables related to canopy openness (higher for A. hirtella), Mg (higher for both species), and K (lower for A. hirtella). A principal components analysis supported these results; A. hirtella was associated with higher canopy openness and Mg, and lower LBC and K. We also report analogous results for nearby sites harboring target species, and demonstrate a probable effect of land cover on soil pH. Our results should inform decisions concerning management of calcareous flatwoods habitats and their characteristic species.