Myers, C. V., R. C. Anderson, and D. L. Byers (Behavior, Ecology, Evolution, and Systematics Section, 4120 Department of Biological Sciences, Illinois State University, Normal, IL 61790-4120). Influence of shading on the growth and leaf photosynthesis of the invasive non-indigenous plant garlic mustard [Alliaria petiolata (M. Bieb) Cavara and Grande] grown under simulated late-winter to mid-spring conditions. J. Torrey Bot. Soc. 132: 1–10. 2005.—Plasticity in photosynthetic response to varied light conditions likely contributes to the successful spread and domination of eastern deciduous forest ground layers by the invasive, non-indigenous plant species Alliaria petiolata. We examined the effects of growing plants with no shading, or under 30% or 60% black shade cloth on leaf photosynthetic rates, maximum rates of leaf photosynthesis (A_max) and stomatal conductance (g_Smax), light compensation point, above and below ground biomass, chlorophyll content and specific leaf mass of A. petiolata grown under simulated late-winter to mid-spring conditions of temperature, photoperiod, and irradiance in a growth chamber. The 0% shade treatment plants exhibited a significantly greater leaf photosynthetic rate than the 60% shade treatment plants between 800 and 1600 μmol·m⁻²·s⁻¹ photosynthetically active photon flux density (PPFD). Leaf A_max was significantly greater for plants grown under no shade than for plants grown under either the 30 or 60% shade treatments and g_Smax was higher for plants grown under no shade than plants in the 60% shade treatment. Plants grown under 0 and 30% shade produced significantly more biomass and had greater specific leaf mass than plants grown under 60% shade. Leaves of the 60% shade treatment had significantly greater chlorophyll a and b content than leaves of the 0 and 30% shade treatments. Our results indicate that A. petiolata displays a plastic response to varied light levels in a way that would likely increase its success in invading eastern deciduous forest ground layers.

Morgan, E.C., and W.A. Overholt (University of Florida Indian River Research and Education Center, 2199 So. Rock Rd., Ft. Pierce FL 34949). Potential allelopathic effects of Brazilian pepper (Schinus terebinthifolius Raddi, Anacardiaceae) aqueous extracts upon germination and growth of selected Florida native plants. J. Torr. Bot. Soc. 132: 11–15. 2005.—Schinus terebinthifolius, or Brazilian pepper, is an exotic invasive plant found throughout much of peninsular Florida. It rapidly colonizes disturbed areas, often forming dense monotypic stands, and displaces native vegetation. In the current study we examined a potential mechanism by which Brazilian pepper has become a major invader of Florida's ecosystems. In laboratory bioassays and greenhouse experiments, germination and biomass accumulation in two native Florida plant species, Bidens alba and Rivina humilis, were negatively affected by irrigation with aqueous extracts of Brazilian pepper leaves. This study illustrates a potential mechanism through which one plant may gain a competitive advantage over another.

Nuzzo, V. (Natural Area Consultants, 1 West Hill School Road, Richford, NY 13835). Demography and habitat of Corydalis flavula (Raf.) DC. (Fumariaceae) in south-western Michigan (U. S. A.). J. Torrey Bot. Soc. 132: 16–23. 2005.—Corydalis flavula (Raf.) DC. is a rare winter annual in Michigan, restricted to two counties in the southwestern portion of the state. Corydalis flavula density, capsule and seed production, and composition and structure of the associated groundlayer and overstory, were recorded 18–26 May 1998 in six 5,600 m² plots. Corydalis flavula plants were sparsely dispersed, averaging 1.4 plants/m² and 1.1% cover in all plots. Over 95% of C. flavula plants produced flowers, and 89% produced seeds. Flowering plants produced an average of 4.0 capsules, each with an average of 3.8 seeds, and seed production averaged 15.1 seeds/flowering plant, and 19.9 seeds/m². Over 11% of plants were browsed by deer, foliage on 3.4% of plants showed insect feeding damage, and 3.7% of capsules showed external attack. Inside capsules, insect attack was more frequent, averaging 11%. The six stands where C. flavula was monitored were relatively similar: young, second growth, disturbed forests, dominated by black locust (Robinia pseudoacacia L.) and subdominated by black cherry (Prunus serotina Ehrh.). Tree density ranged from approximately 750–1250 trees/ha, and dead trees were common, accounting for an additional 28% of all trees > 10 cm dbh. Corydalis flavula presence was associated with shorter groundlayer vegetation (25 cm vs 29 cm) and lower groundlayer cover (96% vs 107%), and abundance was significantly higher in both quadrats and plots with low graminoid cover and high annual and biennial cover. Corydalis flavula, like other woodland annuals, is disturbance adapted, and conditions that favor growth of woodland annuals also favor the growth of C. flavula.

Himes, S. L. (Department of Biology, Western Carolina University, Cullowhee, NC 28723) and R. Wyatt (Highlands Biological Station, 265 Sixth Street, P.O. Box 580, Highlands, NC 28741). Costs and benefits of self-fertility in Asclepias exaltata (Apocynaceae). J. Torrey Bot. Soc. 132: 24–32. 2005.–Variation in levels of self-fertility exists among populations of Asclepias exaltata, despite traditional characterization of this species as self-sterile. The costs and benefits associated with self-fertility were investigated by comparing fruit-set, seed number, and progeny fitness from self-pollinations, single-donor cross-pollinations, and multiple-donor cross-pollinations. Single-donor cross-pollinations were expected to produce fewer fruits than multiple-donor cross-pollinations as a result of mate selection by maternal plants, but this was not the case. Outcrossed fruits from self-fertile plants contained significantly fewer seeds than did outcrossed fruits from self-sterile plants, but overall fitnesses of self-fertile and self-sterile plants were essentially equal. There was variability among self-fertile plants in their propensity to mature selfed fruits, but, on the whole, selfed fruit-set was very low compared to outcrossed fruit-set. Furthermore, seed number, percent seed germination, and plant survival were significantly lower for selfed versus outcrossed progeny on self-fertile plants, suggesting strongly that selfed progeny suffer greatly from inbreeding depression. Because selfing is rare and the overall fitnesses of self-fertile and self-sterile plants are essentially equal, frequencies of self-fertile individuals in these populations may differ simply due to random processes.

Evans, L. S. (Laboratory of Plant Morphogenesis, Biological Sciences Research Laboratories, Manhattan College, the Bronx, NY 10471). Stem surface injuries of Neobuxbaumia tetetzo and Neobuxbaumia mezcalaensis of the Tehuacan Valley of central Mexico. J. Torrey Bot. Soc. 132: 33–37. 2005.—Identical scale and bark stem surface injuries are present on surfaces of fourteen species of long-lived columnar cacti in both North and South America. The purpose of this research was to determine the amounts of injuries on south-, east-, north-, and west-facing stem trough surfaces for two species of columnar cacti, Neobuxbaumia tetetzo and N. mezcalaensis, from the Tehuacan Valley (18° N latitude) of central Mexico. Stem surface injury levels on south (equatorial)-facing surfaces were twice that of north (polar)-facing stem surfaces for both cactus species. Calculations indicate that twice as much total annual direct sunlight occurs to south-facing cactus surfaces than on north-facing surfaces at 18° N latitude. In general, surface injury levels for east-facing and west-facing plant surfaces were usually intermediate between the high levels of injury for south-facing surfaces and the low levels of injury for north-facing surfaces. It should be noted that published results from columnar cacti growing at 32 °N latitude have about four times more stem surface injuries and four times more direct sunlight exposure on equatorial-facing surfaces than on polar surfaces. So, for columnar cacti at 18° and 32° latitude, the ratios of injuires were coincident with ratios of sunlight on equatorial and polar surfaces. Overall, the results of these studies are consistent with the hypothesis that sunlight, possibly UV-B, cause injuries to stems of long-lived, columnar cacti.

Bowers, J. E. (U.S. Geological Survey, 1675 W. Anklam Rd., Tucson, AZ 85745). El Niño and displays of spring-flowering annuals in the Mojave and Sonoran deserts. J. Torrey Bot. Soc. 132: 38–49. 2005.—Although popular and scientific literature frequently assumes a strong connection between El Niño-Southern Oscillation (ENSO) and good displays of spring-flowering annuals in the southwestern United States, such assumptions are based on anecdotal, short-term evidence. The goals of this study were to identify good wildflower years as objectively as possible, to assess the correlation between El Niño and good displays of spring-flowering annuals, and to examine the influence of rainfall amounts on good wildflower years. The terms “good displays” and “good wildflower years” refer to times or places when populations of showy spring-flowering annuals (often called winter annuals) are abundant, robust, and diverse. In the deserts of southeastern California and southern Arizona, good wildflower years occurred about once every 5 to 7 years in the 20th century. The connection between good wildflower years and traditionally defined El Niño episodes was weak, but when El Niño was redefined in a phenologically meaningful way as any calendar year in which the average Southern Oscillation Index (SOI) between July and December was negative, 21 of 27 good wildflower years in the combined deserts were associated with El Niño. Good wildflower years were 3.6 times more likely after redefined El Niño years than after other years. Rain in the months before good wildflower years was at least 30% greater than the long-term average in the Mojave Desert and at least 50% greater in the Sonoran Desert. A diverse flora of spring-flowering annuals occurred in the region during the late Wisconsin and early Holocene, which was a period of wetter, milder winters and cooler summers. Perhaps some species of spring-flowering annuals persist today in the arid southwestern United States only because frequent El Niño conditions recreate the cool, moist conditions of the late Pleistocene.

Kostel-Hughes, F., T. P. Young, and J. D. Wehr. (Louis Calder Center—Biological Field Station and Department of Biological Sciences, Fordham University, P.O. Box 887, Armonk, NY 10504). Effects of leaf litter depth on the emergence and seedling growth of deciduous forest tree species in relation to seed size. J. Torrey Bot. Soc. 132: 50–61. 2005.—Leaf litter has a major impact on soil microenvironmental conditions and so can be an important influence on seedling recruitment and hence plant community structure. We conducted a greenhouse experiment to examine the impact of leaf litter from temperate deciduous forests on the emergence and growth of tree seedlings in relation to seed size. Our treatments were bare (no litter), shallow (1–2 cm deep, 140 g·m⁻²), and deep (ca. 5 cm deep, 420 g·m⁻²) litter. Seed sizes ranged from 0.7–3636 mg. For Betula lenta (seed mass = 0.7 mg), emergence on bare soil was greater than 50%, approximately 12% in shallow litter, and no emergence in deep litter. Percent emergence for Liquidambar styraciflua (seed mass = 6 mg) was highest in bare soil and shallow litter treatments (64–69%) and was reduced by more than 80% in the deep litter treatment. Ailanthus altissima (seed mass = 30 mg) and Quercus velutina (seed mass = 1900 mg) exhibited no significant differences in emergence among litter depth treatments whereas, for Quercus rubra (seed mass = 3636 mg), percent emergence was over 50% greater under deep litter than under shallow litter. Seedling growth also differed in response to the litter treatments. For the two smallest-seeded species, B. lenta and L. styraciflua, seedling robustness (aboveground biomass divided by seedling height) was greatest in the bare treatment. Seedling robustness of Q. velutina decreased with increased litter depth while Q. rubra had its greatest seedling robustness in the shallow litter treatment. For A. altissima, seedling robustness and root:shoot ratio both decreased with increased litter depth. Our results suggest that the two smallest-seeded species are better adapted to colonizing post-disturbance sites where there is likely to be less litter, whereas the two largest-seeded oak species are better-suited to establishing in forests with a thicker litter layer. This is consistent with the communities in which these species typically are found. The enhanced seedling growth of A.altissima in bare-to-shallow litter conditions may be one of the attributes that accounts for the success of this highly invasive non-native species in urban forests in the New York City metropolitan area which have shallower litter than nearby rural forests.

Holmes, K. L., P. C. Goebel (School of Natural Resources, Ohio Agricultural Research and Development Center, The Ohio State University, 1680 Madison Avenue, Wooster, OH 44691), D. M. Hix (School of Natural Resources, The Ohio State University, 2021 Coffey Road, Columbus, OH 43210), C. E. Dygert, and M. E. Semko-Duncan (School of Natural Resources, Ohio Agricultural Research and Development Center, The Ohio State University, 1680 Madison Avenue, Wooster, OH 44691). Ground-flora composition and structure of floodplain and upland landforms of an old-growth headwater forest in north-central Ohio. J. Torrey Bot. Soc. 132: 62–71. 2005.—We compared the ground-flora (vascular plants ≤1 m tall) composition and structure of floodplain and upland landforms, and examined the influence of environmental factors on ground-flora composition and structure, in an old-growth headwater forest in the Western Glaciated Allegheny Plateau Ecoregion of Ohio. Soil pH, percent organic matter, sand content, and clay content were significantly higher on the floodplains than on the uplands, while the upland landforms were characterized by higher percentages of silt. Percent total nitrogen and concentrations of NO₃^--N, P, K, Ca, Mg, Mn and Zn were all significantly higher on floodplain landforms than on upland landforms. While species richness and diversity were similar between landforms, ground-flora composition and structure were different. Canonical correspondence analysis (CCA) associated graminoids and forbs with floodplains, while woody species were associated with uplands. Multi-response permutation procedure (MRPP) demonstrated that floodplains had higher cover of Impatiens capensis, Laportea canadensis, Leersia virginica, and Urtica dioica. Conversely, uplands were characterized by higher cover of Acer saccharum, Fagus grandifolia, Fraxinus americana, Parthenocissus quinquefolia, and Polygonatum pubescens. This study provides much-needed information on the vegetation-environment relationships of headwater riparian forest ecosystems that may be useful for riparian restoration in north-central Ohio.

Grell, A. G. (Arkansas Forest Resources Center, School of Forest Resources, University of Arkansas-Monticello, Monticello, AR 71656-3468), M. G. Shelton (USDA Forest Service, Southern Research Station, Monticello, AR 71656-3516), and E. Heitzman (Arkansas Forest Resources Center, School of Forest Resources, University of Arkansas-Monticello, Monticello, AR 71656-3468). Changes in plant species composition along an elevation gradient in an old-growth bottomland hardwood-Pinus taeda forest in southern Arkansas. J. Torrey Bot. Soc. 132: 72–89. 2005.—Old-growth bottomland hardwood-Pinus taeda L. forests are rare in Arkansas, and the complex relationships between plant communities and environmental conditions have not been well described in these forests. To investigate these relationships, a digital elevation model was developed for a 16.2 ha old-growth bottomland hardwood-Pinus taeda forest in southern Arkansas. Overstory trees, saplings, seedlings, and herbaceous plants were analyzed in three 0.5 m elevation classes and by using indirect gradient analysis. Information was also collected on site factors (canopy cover, forest floor litter cover, and elevation), soil physical factors (bulk density and soil texture), soil moisture, and soil chemical factors (pH, electrical conductivity, organic matter, N, P, K, Ca, Mg, S, Fe, Mn, Zn, Cu, and Na). Importance values for 35% of seedling species, 30% of overstory species, 22% of herbaceous species, and 8% of sapling species differed significantly by elevation class. Significant differences by elevation in species diversity, richness, and evenness were identified in the seedling stratum, while only sapling evenness differed by elevation. Seventy-four percent of the environmental characteristics produced significant differences by elevation except for soil texture (sand, silt, and clay), September soil moisture content, Mn, and Cu. Seventy percent of environmental variables were significantly correlated with elevation. Dominant environmental influences on species composition in all strata included elevation as well as many other correlated variables such as Fe, forest floor litter cover, bulk density, and Na. Results from this study suggest that differences in vegetation were primarily the result of subtle elevational variations. Restoration or management of these forests should carefully consider microtopographical influences.

Arii, K., B.R. Hamel, and M.J. Lechowicz (Department of Biology, McGill University, 1205 Av. Docteur Penfield, Montréal, QC H3A 1B1). Environmental correlates of canopy composition at the Gault Nature Reserve in southwestern Quebec, Canada. J. Torrey Bot. Soc. 132: 90–102. 2005.—The environmental basis for variation in canopy composition was investigated in an extensive old-growth forest at Mont St. Hilaire, Quebec, Canada. Based on 144 permanent plots, spatial variation in canopy tree species and the effect of environmental variables on canopy composition were examined using canonical correspondence analysis (CCA). Slope and the amount of direct solar radiation received during the growing season, both of which are good indicators of soil moisture, were the main factors explaining plot-to-plot variation in canopy composition. Quercus rubra, Betula papyrifera, Ostrya virginiana and Pinus strobus predominated on plots with high insolation and steeper slope, while species such as Acer saccharum, Fagus grandifolia, Betula alleghaniensis, and Tilia americana occurred on sites with gentler slope and lower insolation during the growing season. Additionally, plots with greater dominance of Acer saccharum in the canopy had higher soil nitrogen availability, and plots with greater dominance of Fagus grandifolia had lower Ca availability.

Bryan A. Black and Marc D. Abrams (203 Forest Resources Laboratory, University Park, PA 16802). Disturbance history and climate response in an old growth hemlock forest, central Pennsylvania. J. Torrey Bot. Soc. 132: 103–114. 2005.—Radial growth patterns are examined in relation to the historical development, disturbance history, and climate responses of an old-growth hemlock forest located in central Pennsylvania. Hemlock recruited continuously from the mid 1700s through 1890 with a sharp pulse of regeneration between 1860 and 1870, while white pine formed an even-aged cohort in a narrow interval between 1865 and 1870. No recruitment of any species occurred in the 20^th century, likely because of deer browsing. Isolated pulses in radial growth occurred in almost every decade of the chronology, indicating a high frequency of small-scale disturbances. Major stand-wide pulses in hemlock radial growth occurred around 1810 and 1850. The 1850 event corresponds with the date of two intense windstorms and was the only disturbance event large enough to recruit white pine. Long-term effects of climate were apparent in the 20^th century in which periods of low radial growth occurred in the cool, dry periods of 1910–1930 and 1965–1970. Correlations and response function analysis revealed that hemlock radial growth was limited by drought in winter and early fall, and by low March temperatures.

Broughton, D. A. (Falklands Conservation, PO Box 26, Stanley, Falkland Islands) and J. H. McAdam (Department of Applied Plant Science, The Queen's University of Belfast, Newforge Lane, Belfast, BT9 5PX, UK). A Checklist Of The Vascular Flora Of The Falkland Islands (Islas Malvinas). J. Torrey Bot. Soc. 132: 115–148. 2005.—This paper provides the first comprehensive, updated account of the Falkland Islands native flora for nearly forty years. 171 species are recognised, thirteen of which are endemic. Seven native species are included in the checklist for the first time: Arachnitis quetrihuensis Dimitri, Carex banksii Boott, Carex barrosii Nelmes, Elatine sp., Plantago moorei Rahn, Ruppia filifolia (Phil.) Skottsb. and Viola magellanica Forst. f. The presence of Rumex magellanicus Campd., a record previously considered doubtful, is also confirmed. Three previously reported native species are believed to have been recorded in error for the Falkland Islands, and are removed. These are, Eleocharis albibracteata Nees & Meyen ex Kunth, Plantago maritima L. and Schizaea fistulosa Labill. The checklist provides the first detailed account of the ecology, phenology, distribution and status of the vascular plant flora, and as such is a unique record of the Falkland Islands flora at the beginning of a period of unprecedented economic and social change.

Greller, A.M. (Department of Biology, Queens College, CUNY, Flushing, NY 11367; and Department of Science, Brooklyn Botanic Garden, 1000 Washington Ave., Brooklyn, NY 11225), G. E. Lotowycz (Planting Fields Herbarium and Library, Planting Fields Arboretum, P.O. Box 58, Oyster Bay, NY 11771), G. Moore (Department of Science, Brooklyn Botanic Garden, 1000 Washington Avenue, Brooklyn, NY 11225), E. Lamont (New York Botanical Garden, Bronx, NY 10458), H. Binger (Department of Biology, Queens College, CUNY, Flushing, NY 11367), B. Conolly (Long Island Botanical Society, P.O. Box 507, Aquebogue, NY 11931), V. Dankel (Department of Biology, Queens College, CUNY, Flushing, NY 11367), J. Hoar (Caumsett Foundation, Caumsett State Park, Lloyd harbor, Huntington, NY 11743), C. Johnston (Planting Fields Herbarium and Library, Planting Fields Arboretum, P.O. Box 58, Oyster Bay, NY 11771), A. Mangiacapre (Department of Biology, Queens College, CUNY, Flushing, NY 11367), J. Schmidt (Department of Biology, Queens College, CUNY, Flushing, NY 11367), L. Zimmerman (Department of Biology, Queens College, CUNY, Flushing, NY 11367), V. Luisi (Department of Biology, Queens College, CUNY, Flushing, NY 11367), B. Quigley (Department of Biology, Queens College, CUNY, Flushing, NY 11367), M. L. Lamont (Long Island Botanical Society, P.O. Box 507, Aquebogue, NY 11931), and S. E. Clemants (Department of Science, Brooklyn Botanic Garden, 1000 Washington Ave., Brooklyn, NY 11225). Vascular Flora of Caumsett State Park, Lloyd Neck, Long Island, New York, with notes on the vegetation. J. Torrey Bot. Soc. 132: 149–168. 2005.—Caumsett State Historic Park (CSHP) is a 650 ha tract, 50 km east of New York City, New York. The vascular flora comprises 101 families, 330 genera, and 624 species, of which 405 species (65%) are native and 219 species (35%) are exotic to CSHP. Flowering plants (Division Magnoliophyta) form the bulk of the flora. Magnoliopsida (dicots) account for most of the angiosperm families, genera, and species. Liliopsida (monocots) scarcely account for more than 20% in any category. Pinophyta (conifers) are rare, as are the Lycopodiophyta and Equisetophyta (“fern allies”). Polypodiophyta (ferns) equal all the other non-angiosperm groups, at all taxonomic levels. The most species rich families are Asteraceae, Poaceae, Rosaceae, Fabaceae, Cyperaceae, Liliaceae, Lamiaceae and Brassicaceae, in that order. The largest genera are Carex, Aster, Solidago/Euthamia, Polygonum, and Hieracium, in that order.

Eleven CSHP species are listed as endangered or threatened in New York State (NYS; Young and Weldy 2003). These are Carex abscondita, C. hormathodes, Cenchrus tribuloides, Scirpus georgianus, S. maritimus, Acalypha virg