Preanthesis cleistogamy, a form of self-pollination within an enclosed flower prior to opening, was investigated in eight species of Podostemum from South America (P. comatum, P. distichum, P. irgangii, P. muelleri, P. ovatum, P. rutifolium subsp. rutifolium, P. scaturiginum, P. weddellianum) and the North American P. ceratophyllum. Fluorescence microscopy was used to determine whether pollen tubes were present in the stigmas of unopened flowers from 109 collections. Preanthesis cleistogamy was documented in P. weddellianum, representing the second report of this phenomenon in the genus (previously documented in P. ceratophyllum). The 12 collections with preanthesis cleistogamy represent populations from throughout the geographic range of P. weddellianum. It is hypothesized that preanthesis cleistogamy evolved twice within Podostemum, once in P. ceratophyllum and once in P. weddellianum.

Historical accounts detail numerous uses for poison ivy, poison oak, and other American Toxicodendron spp. (Anacardiaceae), despite their toxicity. The veracity of these accounts has recently been called into question by several sources. In this investigation, a multidisciplinary, hypothesis-driven approach was used to critically evaluate the veracity of such accounts by employing field studies, laboratory experiments, and literature review. Accounts regarding uses in textile production or religious rites were found to be more feasible to evaluate than those pertaining to cooking or medicine. Findings from this study suggest a new interpretation of such accounts and provide novel information regarding both the biology and ethnobotany of these plants.

Isoetes × novae-angliae D.F. Brunt. & D.M. Britton, hyb. nov., represents a sterile hybrid between the tetraploid aquatic pteridophytes I. riparia and I. tuckermanii. It is known only from North Easton, Massachusetts although it formerly likely occurred across the state as well as in Connecticut and southern New Hampshire. Determination of the distribution and nomenclature of this taxon also clarifies the status of a number of early 20th century taxonomic innovations.

Dogwood anthracnose (Discula destructiva) was first discovered in Illinois in 1995 at Dean Hills Nature Preserve, Fayette County. In the original study, individuals of flowering dogwood (Cornus florida) showed a 97% increase in infection by dogwood anthracnose between July 1995 and August 1996. As all size classes of flowering dogwood were infected, it was predicted that the disease would probably cause the extirpation of this species at the site. Though not extirpated, flowering dogwood has not recovered from the initial infection (1995), when 3475 healthy stems/ha were encountered. Since that initial study, total flowering dogwood stems recorded for the site ranged from a low of 110 stems/ha in 1996, to 540 stems/ha in 2002, and 345 stems/ha in 2004.

The vascular flora of Izembek National Wildlife Refuge (NWR), where few previous collections had been reported, was collected and recorded at sites selected to represent the totality of environmental variation. A total of 349 species (339 native and 10 introduced) was identified. To provide a comparative phytogeographic framework, we analyzed data from published reports that categorized vascular plant distribution patterns from a circumpolar, North American, and Alaskan perspective. The native flora of the Izembek NWR primarily includes species of circumpolar (38%), eastern Asian (23%), Eurasian (18%), and North American (13%) distribution. The most important longitudinal distributional classes in North America consist of transcontinental (62%) and extreme western species (31%). The annotated list of species in Izembek NWR expands the range of many species, filling a distributional gap in Hultén's Western Pacific Coast district. Forty notable range extensions are reported. The flora of Izembek NWR is primarily made up of boreal species and lacks many of the species considered to be Arctic. Comparison with the Raunkiaer life-form spectrum similarly points to the boreal.