The impacts of drought have been less studied in terrestrial plant communities than other types of natural disturbance. Most drought studies have focused on regional impacts or used climate modeling over a broad geographic area. This study provides insight into the fine-scale impacts within a single natural community occupying a small area that is more susceptible to drought than its surroundings. This study was conducted on granite bedrock glades in the Huron Mountains in Michigan's Upper Peninsula. In May 2021, prior to drought conditions, 100-m-long transects were established; they were sampled with 1-m² plots in September 2021 after an unusually dry spring and summer. Environmental variables were recorded at two scales (site and plot level), and cover values for alive and top-killed vegetation cover were given for each species. Among the 48 species in our study, 18 experienced at least some top-kill, and 26% of the total vegetation cover was top-killed in 2021. Nonmetric multidimensional scaling ordination was used to explain the variation in top-killed plant data among plots and species. A three-axis solution was reached in PC-ORD with a final stress of 7.55, and a total instability of 0.00 was achieved after 86 iterations. While the measured variables were not strongly correlated with the axes (r² values < 0.07), the plots with the highest dead species cover were on south-facing slopes with no canopy cover. We hope this study can provide some insight into plant community response to drought at fine scales.

This study discusses changes observed in the vascular flora of an old-growth forest on Dome Island in Lake George over a 50-yr period and compares it with observations made by two earlier studies. Our initial surveys conducted in 1973 identified 133 taxa. Repeated surveys brought the total to 165 taxa. During this period one canopy species that was prominent in 1973, Pinus resinosa Aiton, disappeared entirely by 2015. Although nonnative species became established on the island at least as early as 1961, only 16 taxa identified on the island are nonnative, including 3 species considered invasive in New York. Most of the nonnative species are found along the margins of the island, carried to the island from the mainland either by wave action, by birds, or accidentally by people attempting to control shoreline erosion.

Pod dehiscence in legumes is an important process for the release of mature seeds to the environment. An anatomical study of pod development and dehiscence was undertaken with four groups of legumes from commercial sources. Immature, mature, and nearly dehiscent tissue samples were processed from Glycine max, Lupinis sp., Phaseolus vulgaris, and Pisum sativum. All four legume groups had an epidermis, bundle cap cells, and mesocarp cells in their sutures. Soybean pods had a dehiscent zone of fragile cells that the other three legume groups did not have in their dehiscent areas. The dorsal suture of soybean was very fortified with extensive bundle cap cells and lignified epidermal cells. Ventral suture apices of lupines had collapsed cells at a depression on the surface near a small group of bundle cap cells. Unlike the other species, pea samples had only one row of bundle cap cells with a large number of vascular bundles beneath. Immature samples of bean pods had no bundle cap cells. Carpel tissues varied among the four groups of legumes. Lupine and peas had a thickened endocarp early in development that was maintained throughout development while soybean and beans pods only developed a thickened endocarp layer later in development. Most carpel cells had thin cell walls and the majority of these cells collapsed prior to dehiscence. The death of thin-walled carpel cells and the loss of moisture from carpels may have a major role in dehiscence. Overall, carpels of the four groups of legumes had a variety of anatomical characteristics throughout maturity.

Subtropical calcareous wet grasslands (SCWG) are pyrogenic hyper-seasonal grasslands with exceptional vascular plant biodiversity and conservation value in south-central Florida with floristic affinities to southern Florida marl grasslands, and both are dominated by Muhlenbergia sericea. We sampled 62 sites (n = 124 samples), of which 62 were surface soil samples (upper 1–10 cm), and 62 were subsurface soils (above the spodic horizon) across the edaphic-hydrologic gradient of savanna-grassland landscape in south-central Florida. We sought to determine how soil chemistry (17 variables) and texture (7 categories) might correlate with floristic composition and distinguish SCWG from savanna-grassland community types in peninsular Florida. To test which soil PCA axes were associated with plant community types, we used correlations between NMDS plot scores and the scores of significant soil PCA axes. Surface and subsurface soil chemistry were significantly correlated with dimensions of variation in savanna-grassland plant community types. In SCWG, soil chemistry is segregated because of higher Ca, pH, and percentage base saturation in subsurface soils. Lower cation exchange capacity, surface and subsurface soil texture with greater fine sand particles, lower silt, and higher clay content differentiate SCWG. Our results highlight the edaphic-hydrologic distinctiveness of SCWG, which supports previous recognition based solely on floristic and species composition, where calciphilic habitat specialists coexist with plants otherwise characteristic of brackish marsh, acidic grassland, and xeric sands.

Risk factors that make rare plant taxa particularly susceptible to population declines include a self-incompatible breeding system combined with small population size, small range, and isolated populations separated by unsuitable habitat. Phlox pilosa ssp. sangamonensis is an endangered, self-incompatible, and narrowly endemic taxon with isolated population fragments in east-central Illinois. Here we combined a field and genetic study of Phlox pilosa ssp. sangamonensis as a study of its taxonomic status and conservation, especially because some of its remaining populations are small (< 30 flowering individuals). First, we used six polymorphic nuclear microsatellite loci developed for P. pilosa ssp. pilosa to characterize the genetics of 212 individuals in all 10 known populations of P. pilosa ssp. sangamonensis. We tested the taxon's genetic differentiation from congeners in east-central Illinois: two populations of Phlox pilosa ssp. fulgida, two populations of Phlox pilosa ssp. pilosa, and three populations of Phlox divaricata ssp. laphamii. We also quantified reproduction in each population. We surveyed fruit set for three years and tested correlations with flowering population size and distance to other flowering individuals. For one year, we collected data on seed set from successfully formed capsules. Phlox pilosa ssp. sangamonensis was genetically distinct from, and had putatively lower genetic variation, than Phlox divaricata ssp. laphamii, Phlox pilosa ssp. fulgida, and Phlox pilosa ssp. pilosa. Overall genetic diversity in P. pilosa ssp. sangamonensis appeared low, especially in small populations. Fruit set was positively associated with P. pilosa ssp. sangamonensis population size, with larger population (> 100 flowering individuals) fruit set being more than twice as high compared to smaller (< 30 flowering individuals) ones. Across populations, individuals with a greater distance to flowering neighbors also showed reduced fruit set, although the relationship was not as strong as for population size. In the year we studied seed set, we also found a positive association between population size and seed set, with approximately 30% more seeds per capsule being produced in the larger populations relative to small ones. Our data suggest that P. pilosa ssp. sangamonensis is a genetically distinct taxon from nearby Phlox taxa, and its smaller populations could be at risk of further decline, possibly due to mate or pollen limitation, and/or low genetic diversity. Management for this endangered taxon should facilitate recruitment in small (< 100 flowering individuals) populations and maintain habitat quality for the large populations.