Volume 61 – Issue 1 (Mar 1996)

Henry David Thoreau-a name instantly associated with acclaimed philosophical and literary works such as Walden, The Maine Woods, and On Civil Disobedience, among others. Yet how many botanists and plant ecologists realize that it was Thoreau who also coined the term “forest succession” in 1860 to describe the process of vegetation development in New England forests? Throughout his life, but particularly in his later years, Thoreau was an astute student of plant seed dispersal mechanisms, impacts of seed predators on plant regeneration, and the interplay of these two factors in forest succession. Moreover, he was an early advocate of Charles Darwin’s theory of natural selection and strived to frame his observations and writings in plant ecology and natural history in light of emerging evolutionary thought. Thoreau was one of North America’s earliest plant ecologists with an evolutionary perspective.

Noteworthy Collections: Virginia and Maryland

Sensitive joint vetch (Aeschynomene virginica (L.) BSP.) (Carulli and Fairbrothers 1988, Isley 1990, Rudd 1955) is a Federally Threatened annual legume indigenous to tidal freshwater marshes of the eastern United States. The historic range was Pennsylvania, New Jersey, Delaware, Maryland, Virginia, and North Carolina (Schulz 1994). Plants have not been seen in Pennsylvania and Delaware since the late 1800s; only one population is extant in New Jersey; and North Carolina plants are restricted to roadside ditches and cornfields (Schulz 1994). In Virginia, six populations are distributed over four river systems (Schulz 1994). Current distribution and demographic information for A. virginica in Maryland is reported in this paper first for the portion of the coastal plain east of the Chesapeake Bay (Eastern Shore, lower coastal plain, Delmarva Peninsula) and then for the portion west of the Bay (Western Shore, upper coastal plain).

Preliminary results of a floristic survey of Rabun County, Georgia, are presented the staff of the newly established Louise Gallant Herbarium at Rabun Gap-Nacoochee School. The report is based on field work and literature surveys conducted during the growing seasons of 1989 through 1994. As of November 1994, over 1,140 specimens from Rabun County were collected, representing 489 species. Another 325 species are documented in the literature, bringing the total number of species known from Rabun County to 814. The survey documented 185 county records, one state record, four protected species, and fourteen special concern species. Eight plant communities are described: 1) Chestnut or Oak-Chestnut Communities, 2) Oak and Oak-Pine Communities, 3) Mixed Mesophytic Communities or Cove Hardwoods, 4) Balds, 5) Cliffs and Gorge Walls, 6) Mountain Bogs, 7) Mountain River and Flood Zone, and 8) Disturbed Areas.

St. Francis National Forest is at the southernmost end of Crowley’s Ridge in Lee and Phillips Counties of Arkansas. Most of the Forest is located on Crowley’s Ridge and has narrow ridges and valleys carved into the loessal soils. A small portion of the Forest is located along the Mississippi and St. Francis Rivers and is characterized by level, alluvial soils. This study identified 104 vascular plant families, 285 genera, 424 species and 11 subtaxa on the Forest. The study was begun in the fall of 1989 and completed in the spring of 1991.

Flowering individuals are rare in populations of false hellebore in Illinois. In the fall of 1993, however, flowering was observed in 16 of 31 populations from east-central Illinois. Of the 96 flowering individuals found, 70 produced fruits. Seed production was low; 75% of the capsules produced 0-3 seeds.

Rhododendron maximum L. restricts regeneration of overstory species; however, the mechanisms are poorly understood. Three treatments were used to examine the effects of R. maximum germination success and survival of Acer rubrum L. under a closed overstory canopy: (1) R. maximum understory, (2) open understory, and (3) open understory with shadecloth. Shadecloth treatments mimicked the low light conditions beneath R. maximum (<5 % full sun) while controlling for R. maximum forest floor influences. Soil moisture was significantly lower under R. maximum than under open or shadecloth treatments. Initially, Acer rubrum survival was similar for open understory and shadecloth treatments, while germination and survival in R. maximum plots were low. After approximately 20 d, mortality in the shadecloth treatment increased and survival rates were less than 5% by the end of the sampling period. Survival in the open understory treatment stabilized at >2✕ that observed under shadecloth, while percent germination and survival in R. maximum plots were lower than in either of the other treatments throughout the sampling period. These results suggest that in addition to the light limitation associated with R. maximum, edaphic effects such as low soil moisture or allelopathic compounds may inhibit Acer rubrum success.

Data in Bessey C. Picklesimer’s (1927) unpublished M.A. thesis on the vegetation analysis of a cedar glade in the Central Basin of Tennessee are put into a format that will allow them to be used by ecologists, and the results are compared with those of other quantitative studies on cedar glade plant communities in the Basin. Picklesimer’s study is significant because it contains the most comprehensive data set available documenting the importance of the two shallow-soil dominants Arenaria patula and Sedum pulchellum in the vegetation of cedar glades in the Central Basin. The results of her vegetation analysis are in general agreement with those of previous workers in that: (1) the C3 winter annual dicots S. pulchellum, A. patula, and Leavenworthia spp. are major spring-aspect dominants of xeric open glades; (2) the C4 summer annual grass Sporobolus vaginiflorus is the primary dominant of subxeric open glades in summer; (3) Forestiera ligustrina, Symphoricarpos orbiculatus, and Rhus aromatica are the dominant shrubs in glade thickets/woods; and (4) Juniperus virginiana, Celtis laevigata, and Ulmus alata are the most important trees in glade woods. Floristic similarities and dissimilarities between the cedar glade studied by Picklesimer and those studied by other vegetation ecologists in the Center Basin are discussed.

The Monkey-face Orchid, Platanthera integrilabia, was locally common on the Cumberland Plateau of Kentucky and Tennessee prior to the 1940s, but is currently a C2 candidate for United States protection as an endangered species. Insect pollination of this orchid is described for the first time at the largest remaining population of the species, located in McMinn County, Tennessee, just prior to peak flowering (12-15 August 1992). Despite the orchid having flowers adapted to sphingid moth pollination, three day-flying Lepidoptera (Epargyreus clarus, Papilio glaucus, and P. troilus) carried pollinia on com- pound eyes and were pollinators. Over half of all flowers (624 of 1,096 or 56.9%) set fruit two months after flowering. A mean of 4.7 capsules per inflorescence and 3,433 seeds per capsule was recorded. The survival of P. integrilabia will likely depend on the continued existence of the McMinn County population as a seed source for a vigorous program to reestablish seedlings in suitable habitats.

James and Melinda Harris have produced an excellent text on plant identification terminology that includes over 2,400 botanical terms. Seventeen hundred illustrations help clarify the meaning of the botanical terminology used in plant identification keys.