Volume 63 – Issue 4 (Dec 1998)

Morphological features were examined from more than 5,000 Rubus specimens to prepare the first comprehensive revision of the native and naturalized Rubus of Iowa. Twenty-eight species (one with two varieties) and one interspecific hybrid have been collected in the state. They are described in this revision, which contains keys to subgenera and species designed specifically for field researchers in Iowa and nearby states. Synonymy, distribution, phenology, habitat, associated plants, and taxonomic treatment by past researchers are also discussed.

Range-wide county distribution maps are presented for 22 species representing Rubus subgenus Rubus (the blackberries and dewberries), and Iowa county distribution maps have been included for R. idaeus L. var. strigosus (Michx.) Maxim., R. occidentalis L., R. parvifolius L., and R. pubescens Raf.

The findings of this study are discussed in the context of the putative reticulate phylogeny among species of Rubus subgenus Rubus, and potential subjects for future molecular and cytological research are proposed.

Based on the examination of 1,400 specimens, descriptions and distributions are provided for the five taxa of Proserpinaca in the southeastern United States. Proserpinaca palustris var. palustris, P. intermedia and P. pectinata occur primarily in the Atlantic and Gulf Coastal plains, while P. palustris var. amblyogona occurs in the Mississippi embayment area and P. palustris var. crebra occurs throughout the Southeast.

A former oak-chestnut forest community on the southwest-facing slope of Beanfield Mountain in the Mountain Lake area of southwestern Virginia, previously sampled in 1939 and 1969-70, was resampled during the summer of 1993 to assess the successional changes in forest overstory composition that have taken place following the chestnut blight. In 1939, an oak complex dominated by white oak (Quercus alba), chestnut oak (Q. prinus), and red oak (Q. rubra) had replaced the original oak-chestnut forest. The 1969 70 study found that pignut hickory (Carya glabra) had become the leading dominant on the slope, with red oak and chestnut oak the most important codominants. However, by 1993 hickory had decreased in importance, and red maple (Acer rubrum) had become a canopy codominant. Red oak and chestnut oak were still the dominant oaks, but black birch (Betula lenta) also had become a consistent component of the community. As such, nearly seventy-five years following the blight, oaks have maintained their codominant status. Hickory is less important than in 1969-70, whereas red maple and black birch are more important.

The current checklist of Tennessee vascular plants, published in 1993, and the two-volume atlas of distribution maps of the state’s flora, published in 1993 and 1997 (and now available electronically), were compared and reconciled with volume 2 (pteridophytes and gymnosperms, published 1993) and volume 3 (dicots: Magnoliophyta: Magnoliidae and Hamamelidae, published 1997) of the Flora of North America (FNA). Numerous differences were found, including: (1) 18 taxa documented in the checklist/atlas that were not credited to Tennessee by FNA; (2) 15 FNA-listed taxa that apparently are additions to the Tennessee flora; (3) seven checklist/atlas taxa that were reduced to synonymy by FNA; (4) 40 checklist/atlas taxa that, in FNA, were changed taxonomically or nomenclatorially, transferred to another family, or some other discrepancy occurs. All changes are presented in tabular form.

To determine the extent to which pollinator scarcity and/or specificity may account for the rarity of Ribes echinellum, and to provide information for protection, pollinators and pollinator behavior were observed. The primary pollinators at both Florida and South Carolina stations were large bees including species of Bombus, as well as Habropoda laboriosa. The pollinators are widespread, at least locally common, and are not host-specific, apart from an association with pendent blossoms in Habropoda laboriosa. Although neither pollinator rarity, nor pollinator specificity, appear to provide an adequate explanation for the rarity of Ribes echinellum, high floristic diversity in relicts of mesophytic forest may contribute to the persistence of the rare shrub by maintaining the large bee populations necessary for cross-pollination. The bees land on the pendent flowers immediately assuming an inverted position while grasping the reflexed calyx lobes and petals with hindlegs, and stamens and style with forelegs. In this position the anthers and style tips are brought into contact with the ventral thorax and abdomen, while the bee probes the floral tube. Protandry and circumstantial evidence suggest a reliance on pollinators for fruit development.

This 20-year study reports on changes in the structure and composition of an old-growth forest after a windstorm in 1974. Tree density, basal area, and species composition were measured at Dinsmore’s Woods, an old-growth maple-dominated forest in Boone County, Kentucky in 1973, in 1974 following a tornado and again in 1985 and 1994 to assess recovery patterns. Tree density and total basal area declined from 1974 to 1985 but increased in 1994. Species composition of the canopy was unchanged, with Acer saccharum as the dominant species and a subdominant stratum composed of Fraxinus americana, Ulmus rubra, Celtis occidentalis, and Quercus spp. However, Acer saccharum has increased in dominance relative to subdominants, except Quercus spp. The dominance of Acer saccharum was seen at all strata (canopy, saplings, and seedlings). The disturbance appears to have increased the dominance of Acer saccharum. This study indicates that this catastrophic windstorm decreased species diversity in this forest community.

Noteworthy Collections: North Carolina, Virginia, and Georgia

Previous keys to the genus Sarracenia L. use characters of pitchers along with flowers and phyllodia, the latter two being limited to the spring flowering season and autumn respectively. Such keys, though useful in season, are heavily dependent on whether these structures are present. I present a key using pitcher characters only that can be used through the entire growing season and complementing previous keys.

Amaranthus pumilus Raf. (Amaranthaceae), Seabeach amaranth, is a federally-threatened summer annual plant species endemic to Atlantic Coastal Plain beaches in New York, North Carolina, and South Carolina. Historically, its range included nine states from Massachusetts to South Carolina. Thus, it has been extirpated from Delaware, Massachusetts, Maryland, New Jersey, Rhode Island, and Virginia (U.S. Fish and Wildlife Service 1993). As a contribution to the autecology and ex situ conservation of this rare “fugitive” (or pioneer) species of nonstabilized beaches (U.S. Fish and Wildlife Service 1993), we determined its seed dormancy breaking and germination requirements.

As a botanist, I like books that help me to learn about plants from around the world, especially those related to our native species. This often means books about cultivated exotic plants that can be grown here in Eastern North America. From this we ascertain that in other northern countries where the climate is similar to ours, the families, genera and species are often closely related or at least similar in growth form to ours. This is especially true of conifers, where our native species are very similar to those in Europe and eastern Asia.