Volume 83 - Issue 1 (May 2018)

Ward, Daniel B. 2017. Thomas Walter and His Plants. The Life and Works of a Pioneer American Botanist. Memoirs of the New York Botanical Garden, Vol. 115, Heritage Series, Number 2. Bronx, New York. 220 p. Hardbound. $59.99. ISBN 978-0-89327-539-6.

Thomas Walter (1740?–1789?) is a mystery man in many respects. His birth place and date are uncertain; the year of his death is in doubt. His supposed portrait is that of another man. Yet, Walter is an important figure in American botany. Walter’s Flora Caroliniana (1788) is the earliest regional flora using Linnaeus’ binomial nomenclature and sexual system of classification. Many well-known flowering plants were first described in Walter’s Flora, including Aesculus parviflora, Carpinus caroliniana, Cypripedium reginae, Frasera caroliniensis, Magnolia fraseri, Sarracenia rubra, and Utricularia inflata—all Walter’s coinages.

ABSTRACT Large expanses of loess hill prairie were once common along the bluffs of the Mississippi and Illinois rivers of Illinois. These communities occur in forest openings on thick loess deposits overlying bedrock and frequently have expanses of exposed limestone at their margins (glades). Warm season, clump-forming grasses dominate the herbaceous vegetation along with a mixture of prairie and open forest species. Miles Hill Prairie, Monroe County, Illinois is located about 20 km west of Waterloo in the Northern Section of the Ozark Natural Division. Within the prairie, 148 vascular plant species were recorded with 40 species found in the survey plots. Schizachyrium scoparium dominated followed by Andropogon gerardii, Solidago speciosa, Sorghastrum nutans, and Bouteloua curtipendula. Common forbs include Pycnanthemum pilosum, Symphotrichum patens, and Symphotrichum oolentangiense with Cornus drummondii the most abundant shrub, and Torilis japonica the only exotic species in plots. This is a high-quality loess hill prairie that is well maintained by prescribed fire and brush removal. Most species encountered were common to loess hill prairies, with the 19 exotic species being rare and mostly restricted to prairie edges.

ABSTRACT Old-growth forests provide unique insight into historical compositions of forests in the eastern United States. Plots established within a mixed forest community within Marshall Forest in Rome, Georgia, in 1960 (and remeasured in 1989) were reassessed to determine changes in forest composition. The community has experienced approximately 10% increase in basal area since the previous measurement period. However, changes in species importance have occurred. Chestnut oak (Quercus montana), mockernut hickory (Carya tomentosa), white oak (Quercus alba), and flowering dogwood (Cornus florida) have all decreased in importance, while pignut hickory (Carya glabra), winged elm (Ulmus alata), yellow poplar (Liriodendron tulipifera), and red maple (Acer rubrum) have all increased in importance. Additionally, there are no Pinus spp. saplings in the study area, indicating seedlings are not being recruited into the midstory. These changes indicate continued succession to a composition increasingly dominated by shade-tolerant species. The mixed forest community appears to be transitioning to an oak-hickory community. The assessment of late successional dynamics may help managers of similar forests to determine the best plan of action if they desire to maintain a mixed forest ecosystem.

ABSTRACT Mountain stewartia (Stewartia ovata) is the only member of the family Theaceae endemic to Tennessee. Apart from its physical description and rarity, little is known about this woody understory species. Accounts of stewartia populations and range descriptions are longstanding, but microsite descriptions are limited in detail. We quantified microsites supporting populations of stewartia across East Tennessee as a first step in determining whether stewartia is rare because of rare or altered habitat, limited sexual reproduction, poor dispersal, or a combination of these factors. Five populations of stewartia averaging 7.40 – 1.08 stems per population were inventoried across four East Tennessee counties. Soils on all sites were strongly acidic, highly permeable, well-drained, cobbly loams associated with steep slopes and higher elevations and were low in phosphorus, potassium, calcium, and magnesium. A dense overstory comprised of sourwood (Oxydendrum arboreum), eastern hemlock (Tsuga canadensis), white oak (Quercus alba), eastern white pine (Pinus strobus), red maple (Acer rubrum), and mockernut hickory (Carya tomentosa) resulted in 7.05% – 1.41% of full photosynthetically active radiation (PAR). The midstory and understory were dominated by eastern white pine, red maple, and eastern hemlock. Quantification of stand-level conditions in extant stewartia populations suggested similarities in soil pH, nutrient levels, drainage, overstory composition and structure, and PAR levels. Certain conditions in stewartia sites were unique in the region, suggesting that habitat may limit populations along with other factors. Further investigations of stewartia reproductive ecology, dispersal, and habitat requirements will be key to conserving this species.

ABSTRACT Twenty-seven species, new to the flora of Georgia, are reported here and validated by cited voucher specimens at the University of Georgia (GA) and Valdosta State University (VSC) herbaria, the two largest herbaria in the state. Reassessment and comparison of these collections data have been greatly facilitated by specimen digitization efforts, especially those fostered among herbaria by the GA–VSC Herbaria Collaborative and by the Southeast Regional Network of Expertise and Collections (SERNEC). Four species (Chelone lyonii, Prunus hortulana, Sporobolus arcuatus, and Symphyotrichum simmondsii) are likely native to Georgia and represent range extensions from nearby states. Chelone lyonii and Sporobolus arcuatus are rare and state-ranked critically imperiled (S1) by the Georgia Department of Natural Resources. The 23 exotic species are more or less naturalized or have potential to naturalize in the state. These nonnatives are escapes from cultivation (15 species) or weedy plants (eight species) that are widespread elsewhere and not typically cultivated. Four species (Cleome monophylla, Lobelia pedunculata, Quercus myrsinifolia, and Sedum emarginatum) are putative first records for the flora of North America, at least as occasional escapes.

Oenothera riparia Nutt. (ONAGRACEAE) – Charleston and Colleton Counties: In the drawdown zone on both the Charleston and Colleton County sides of the Edisto River near Jacksonboro, South Carolina, dozens of plants were observed growing primarily around stumps and on logs adjacent to both freshwater tidal swamp forests and freshwater tidal marshes along a 12 km stretch of river. Nearby swamp forest species overhanging the O. riparia plants frequently included Acer rubrum L., Liquidambar styraciflua L., Morella cerifera (L.) Small, Platanus occidentalis L., Taxodium distichum (L.) Rich., and Viburnum nudum L. Oenothera riparia was also observed growing adjacent to former rice impoundments composed of freshwater tidal marshes dominated by Pontederia cordata L., Sagittaria lancifolia L., Spartina cynosuroides (L.) Roth, and Zizania aquatica L. Native vines, Apios americana Medik. and Clematis crispa L., co-occurred with O. riparia along the banks of the Edisto River adjacent to both swamp forest and marsh habitats. Specimens of this O. riparia population were vouchered at The Citadel Herbarium (CITA), 32845052.4200N, 80826048.4400W, 8 July 2016, J.M. Gramling s.n. (CITA-2455, CITA-2456, & CITA- 2457) and later collected by Daniel Castillo s.n. at the same site, 13 June 2017 (USCH).

Significance.

Commonly called the riverbank evening primrose, O. riparia is a southeastern Coastal Plain endemic known from the Cape Fear andWaccamaw River systems in North and South Carolina and in southeastern Virginia from the Northwest and North Landing Rivers. In South Carolina, this species was previously known to occur only in the Waccamaw River Basin and has been collected from the banks of the Waccamaw, Greater Pee Dee, and Black Rivers in that basin system (Weakley 2015). The Black River in Georgetown County was previously considered the southernmost occurrence of O. riparia. The Edisto River population represents two new county records and extends the southern limit of this taxon by roughly 120 km to the southwest. NatureServe has it ranked as a G2– Globally Imperiled to G3–Globally Vulnerable taxon, but no state rank has been assigned (NatureServe 2017). We would recommend that O. riparia be listed as S2–Imperiled in South Carolina, indicating that this plant is likely made up of fewer than 20 populations statewide.

Ribes americanum P. Miller (Grossulariaceae)— MARYLAND, Frederick County: Jefferson, mid-successional floodplain forest, on wetland edge. Exact geographic coordinates are currently withheld until the United States National Park Service can ensure the long-term protection and viability of the population. Significance. In the summer of 2016, a new population of Ribes americanum was discovered during surveys for rare plant species within the Chesapeake and Ohio Canal National Historical Park, a unit of the United States National Park Service in Maryland. The sole historical record of R. americanum in Maryland was documented by John Bitting Smith Norton in 1902 in Carroll County, Maryland

ABSTRACT Cyathium morphology of Euphorbia spathulata from three populations in central Virginia was studied from early developmental stages through nominal anthesis, defined by exposure of the cyathium to the external environment by divergence of paired subtending cyathophylls. Observations were made via dissecting microscope, compound light microscope sections, and scanning electron microscopy. The plants studied revealed a consistent pattern of asynchronous stamen and pollen development as well as a series of predictable changes in style and stigma orientation. Initially, styles and stigmas of pistillate flowers maintain a near-axial (erect) position. Later, when still enclosed by subtending cyathophylls, styles reflex, placing stigmas near early developing anthers shedding pollen. Pollen grains observed on stigmas at this stage indicate cleistogamous pollination. Eventually, paired cyathophylls diverge, exposing the cyathium to the external environment; at this stage, styles and stigmas assume an ascendant position as late-maturing anthers shed pollen, a configuration conducive to chasmogamous pollination. These observations indicate that a succession of cleistogamy and chasmogamy characterize the reproductive process of each cyathium of E. spathulata, at least in the populations studied.

ABSTRACT The genus Isoetes is known for morphological convergence and a relative paucity of useful gross morphological characters for identification. Thus, the chromosome complements of Isoetes spp. are key attributes for species delimitation. Like many other plant lineages, polyploidy and reticulate evolution are important drivers of speciation in Isoetes. In the southeastern US Isoetes flora, polyploidy is common. We used a rapid DNA flow cytometry protocol to generate C values for four diploid, one tetraploid, and one hexaploid Isoetes species and conducted preliminary cytological investigations of two communities of Isoetes. Our work showed noteworthy variation in diploid Isoetes 1C values (1.39 to 3.32), including the smallest 1C value reported for the genus, Isoetes melanopoda ssp. silvatica. The hexaploid species, Isoetes microvela had the highest 1C value (4.21), and the tetraploid species evaluated had an intermediate 1C value (3.37). However, based on the variation in diploid 1C values measured, a simple 23, 43, 63 ratio of C values was not apparent for diploids, tetraploids, and hexaploids, respectively. All Isoetes taxa measured had significantly different 1C values and homogenous C values were observed in two communities of Isoetes (n¼24). These results indicate that DNA flow cytometry may prove a useful tool for routine Isoetes species identification, systematic work, and population-level surveys of Isoetes ploidy level.