Olson, M. E. (Instituto de Biología, Universidad Nacional Autónoma de México, Tercer Circuito s/n, C.U., Copilco, Coyoacán A. P. 70–367, C. P. 04510, México, D. F., México). Wood, bark, and pith anatomy in Pittocaulon (∼Senecio, Asteraceae): water storage and systematics. J. Torrey Bot. Soc. 132: 173–186. 2005.— Anatomy of wood and bark are described for all five species of Pittocaulon, the stems of which consist of a very thick, water storing pith surrounded by a thin-walled cylinder of xylem which is in turn surrounded by a thick, water-storing parenchymatous bark with a wide cortex. The samples examined came from a wide range of water availability, but showed only slight or no differentiation in vessel diameter or other characteristics that commonly track water availability closely. These observations are offered as supporting the hypothesis that the xylem of water-storing plants exists in a selective environment that is in many ways more similar to that of mesic plants than to that of sympatric conventional woody plants. It is hypothesized that the Young's modulus of the small amount of wood present is high, and that the parenchymatous cortex, which has collenchyma beneath the periderm in all species, contributes significantly to the support of the stems. The strata of the chambered pith in Pittocaulon may expand and contract with varying amounts of stored water. Pittocaulon praecox and P. velatum share a lack of sclerified elements in the bark and fusiform cell nuclei. Fibers and druses in the bark may be synapomorphies of the P. bombycophole P. filare P. hintonii clade.

Thomas, J. R., D. J. Gibson (Department of Plant Biology, Southern Illinois University, Carbondale, IL 62901-6509), and B.A. Middleton (National Wetlands Research Center, Lafayette, LA 70506) . Water dispersal of vegetative bulbils of the invasive exotic Dioscorea oppositifolia L. in southern Illinois. J. Torrey Bot. Soc. 132: 187–196. 2005.—Riparian corridors promote dispersal of several species of exotic invasives worldwide. Dispersal plays a role in the colonization of exotic invasive species into new areas and this study was conducted to determine if the invasiveness of Dioscorea oppositifolia L. (Chinese yam) is facilitated by secondary dispersal of vegetative diaspores (bulbils) by water. Since seed production of this plant has not been observed in the United States, bulbils represent the only means of dispersal to new habitats. Dispersal was monitored by placing aquatic traps, tethered bulbils, and painted bulbil caches in a tributary of Drury Creek, Giant City State Park, Illinois. Results indicate that high-energy flow in the creek accelerated secondary dispersal of bulbils downstream and onto the floodplain. The longest recorded dispersal distance was 206.2 m downstream. Dispersal distance of tethered bulbils was not related to rainfall or flow velocity in the creek; however the total number of bulbils trapped was positively related to flow velocity. We conclude that secondary dispersal by water in streams can facilitate dispersal of vegetative bulbils of this exotic species.

Shimamura, R., N. Kachi (Department of Biological Sciences, Graduate School of Sciences, Tokyo Metropolitan University, Hachioji 192-0397, Japan), H. Kudoh (Department of Biology, Faculty of Science, Kobe University, Kobe 657-8501, Japan), and D. F. Whigham (Smithsonian Environmental Research Center, Edgewater, MD 21037). Visitation of a specialist pollen feeder Althaeus hibisci Olivier (Coleoptera: Bruchidae) to flowers of Hibiscus moscheutos L. (Malvaceae). J. Torrey Bot. Soc. 132: 197–203. 2005.—We investigated visitation of a bruchid seed beetle, Althaeus hibisci Olivier, to flowers of Hibiscus moscheutos L. (Malvaceae) under natural conditions. We examined movement of the beetle among flowers that were in different developmental stages, the correlation between corolla size and pollen production, and the correlation between beetle density and corolla size. Beetles moved diurnally from wilted Hibiscus moscheutos flowers that had opened on the previous day to newly open flowers. Beetles did not move to unopened flowers as long as petals were covered by sepals. The results demonstrate that the beetles use corollas as a cue to locate flowers. Hibiscus moscheutos flowers produced pollen in proportion to corolla size; therefore, beetles visiting larger flowers had a high probability of finding larger amounts of pollen. We detected positive correlations between beetle density and petal area when beetles were abundant. Although the correlation coefficients were small (r = 0.24–0.32), they were statistically significant or marginally significant. On the other hand, the correlations were not significant when the density of beetles was low suggesting that the preference for larger flowers is not always detectable and its strength varies with beetle density under natural conditions.

Trager, M. D. (Dept. of Wildlife Ecology and Conservation, University of Florida, Gainesville, FL 32601), E. S. Menges (Archbold Biological Station, PO Box 2057, Lake Placid, FL 33862), P. F. Quintana-Ascencio (Dept. of Biology, University of Central Florida, Orlando, FL 32816), and C. W. Weekley (Archbold Biological Station, PO Box 2057, Lake Placid, FL 33862). Outcrossing effects on the reproductive performance of Hypericum cumulicola, an endangered Florida scrub endemic. J. Torrey Bot. Soc. 132: 204–213. 2005.—We investigated the effects of self-fertilizing and within-population outcrossing in two populations of Hypericum cumulicola, a perennial herb endemic to xeric scrub habitats on central Florida's Lake Wales Ridge. To examine the relationship between pollen source and reproductive performance, we compared fruit set, seed set, percent germination and net fertility (mean number of seedlings produced per flower within a pollination treatment) of hand-pollinated selfed and outcrossed flowers. There were no significant effects of categorical pollen source (self, near outcross, far outcross) on fruit set, and logistic regression showed no effect of interplant distance. Overall and at one of the two populations, far outcrosses had higher seed set than selfs and we found a weak but significant positive correlation between outcrossing distance and seed set. Percent seed germination was unaffected by pollen source. Net fertility was significantly correlated with outcrossing distance overall and at one of the two sites. These results show that pollen source may influence reproductive performance in Hypericum cumulicola, but the effects are fairly weak and inconsistent among populations, suggesting that outcrossing distance is not an important factor affecting small-scale population dynamics of this species.

Cheplick, G. P. (Department of Biology, College of Staten Island, City University of New York, Staten Island, NY 10314). Biomass partitioning and reproductive allocation in the invasive, cleistogamous grass Microstegium vimineum: Influence of the light environment. J. Torrey Bot. Soc. 132: 214–224. 2005.—Biomass partitioning and allocation to chasmogamous (CH) and cleistogamous (CL) reproduction were investigated in the invasive, summer annual Microstegium vimineum in relation to light conditions. This shade-tolerant grass weed of Asian origin forms dense populations in the understory of moist deciduous forests in eastern North America. In autumn each flowering tiller produces one terminal raceme with CH spikelets and 2 to 7 sheath-enclosed axillary racemes with CL spikelets at the uppermost nodes. In a greenhouse, plants were reared from seed families collected from individuals in subpopulations of shady (2 to 8% full sun) or sunny, edge habitats. At maturity, tillers of the shade subpopulation showed greater allocation to leaves, but reduced allocation to CH and CL, compared to those from the sunny subpopulation, suggesting adaptive differentiation to light conditions in the field. Maternal family (within subpopulation) had a significant effect on CH allocation and the mean mass of CH and CL seeds. For mature tillers collected directly from the field habitats, allocation to CH and CL was lowest, and allocation to leaves was greatest, in deep shade. CH and CL allocation averaged 16% and 11%, respectively, in the sunny habitat, but only 6% and 7% in the shady habitat. There was no evidence of a trade-off in allocation to CH vs. CL in field-collected or greenhouse tillers; in fact, there was a significant positive correlation of CH with CL allocation. The ability to grow and allocate limited resources to seed production in CH and CL spikelets under deep shade where other herbs are uncommon, is crucial to the success of M. vimineum as an aggressive colonizer of disturbed forests.

Bertin, R. I., M. E. Manner, B. F. Larrow, T. W. Cantwell, and E. M. Berstene (Biology Department, College of the Holy Cross, Worcester, MA 01610). Norway maple (Acer platanoides) and other non-native trees in urban woodlands of central Massachusetts. J. Torrey Bot. Soc. 132: 225–235. 2005.—We investigated the contribution of non-native tree species to woodlands in and near Worcester, a city of 170,000 residents in central Massachusetts. We sampled species composition of canopy, sapling and seedling layers in 32 woodlands. At three additional sites, we collected additional information on Norway maple, including size/age data, abundance with respect to distance from woodland edge, and apparent mortality compared to that of other species. In all, we encountered 66 tree species, of which 28 were introduced. The most common non-native trees were Norway maple (Acer platanoides L.), black locust (Robinia pseudoacacia L.) and tree-of-heaven (Ailanthus altissima (Miller) Swingle). The last two are shade-intolerant, and there was little evidence that they invade intact woodland. Young Norway maples, in contrast, can persist for decades in the understory. Norway maple comprised 11% of all trees sampled, and 23% of all seedlings and saplings. Its wind-borne seeds dispersed tens and occasionally hundreds of meters away from seed sources into woodland. Because its mortality was lower than or equal to that of most competing species, it is likely to increase in abundance. Young Norway maples were more common on disturbed sites and those near seed sources. Norway maple trees were less common on wet and dry sites than on mesic sites. Because of its widespread use as an ornamental, its capacity to invade intact woodlands and its dense shade, Norway maple has the potential to profoundly alter native woodlands, especially on mesic sites. Mesic woodlands in Worcester are likely to see a decline of species with low to moderate shade tolerance, like white ash (Fraxinus americana L.), red oak (Quercus rubra L.) and black locust, and an increase in shade-tolerant species, including Norway maple. Dry woodlands are likely to remain dominated by a mixture of native oaks, especially black oak (Quercus velutina Lam.).

Elliott, K. J. and J. M. Vose (Coweeta Hydrologic Laboratory, Southern Research Station, USDA Forest Service, Otto, NC 28763). Effects of prescribed burning on shortleaf pine (Pinus echinata Mill.)/mixed-hardwood forests. J. Torrey Bot. Soc. 132: 236–251. 2005.—We examined the effects of a single dormant season fire on overstory and understory species diversity and composition and tree seedling regeneration patterns the first and second years following a prescribed burn in the Conasauga River Watershed of southeastern Tennessee and northern Georgia. We asked: Can a single dormant season fire initiate a trajectory of overstory and understory species change consistent with restoring Pinus echinata/mixed-oak/bluestem (Andropogon gyrans and Schizachyrium scoparium)-grass community types? Six sub-watersheds (similar in vegetation, soil type, stream size, and disturbance history) were located within the Conasauga River Watershed; four of the sites were burned in March 2001, and two sites were designated as controls. Within each site, vegetation was measured in layers: the overstory layer (trees ≥ 5.0-cm DBH), the midstory layer (woody stems < 5.0-cm DBH and ≥ 0.5 m height), and the ground flora layer (woody stems < 0.5-m height and all herbaceous species). All plots were sampled before the prescribed burn (Sept. 2000) and after the burn in July of 2001 and 2002. Consistent with the goals of the land managers, all the prescribed fires resulted in low-to-moderate intensity and low severity fires. However, we found no significant change in overstory, midstory, or ground flora species diversity after burning. We found no regeneration of P. echinata seedlings after the prescribed fire. Although fire reduced basal area of woody species in the midstory, prolific sprouting from hardwoods resulted in higher density of fire-sensitive hardwoods such as Acer rubrum, Oxydendrum arboretum, and Nyssa sylvatica. Density of Pinus strobus, an undesirable species, was reduced by 20% and its basal area was reduced by 50% after the burn. Overstory mortality occurred in small size class hardwoods as a result of the fire, but most of the mortality occurred in P. echinata and P. virginiana Miller due to infestation with pine bark beetles. The prescribed fires were not of sufficient intensity to: reduce overstory basal area, prepare a seedbed for successful pine germination, affect diversity of any of the vegetation layers, or promote A. gyrans and S. scoparium recruitment. Thus, additional fire treatments or a combination of fire and thinning treatments will be necessary to restore these ecosystems to P. echinata/mixed-oak/bluestem grass community types.

Forrester, J. A. (SUNY, College of Environmental Science and Forestry, 1 Forestry Drive, Syracuse, NY 13210-2778), T. E. Yorks (Environmental Studies Program, Cazenovia College, 22 Sullivan Street, Cazenovia, NY 13035) and D. J. Leopold (SUNY, College of Environmental Science and Forestry, 1 Forestry Drive, Syracuse, NY 13210-2778). Arboreal vegetation, coarse woody debris, and disturbance history of mature and old-growth stands in a coniferous forested wetland. J. Torrey Bot. Soc. 132: 252–261. 2005.—We quantified the forest age and tree size structure of an old-growth and mature stand in a coniferous forested wetland in central New York, USA. We also determined the volume and decay class distribution of standing and downed coarse woody debris. The old-growth stand contains eastern white pine (Pinus strobus L.) > 400 years old and other species > 200 years old. Live tree basal area in the old-growth area (36 m²·ha⁻¹) was dominated by approximately equal amounts of balsam fir (Abies balsamea (L.) Miller.), eastern white pine, and northern white-cedar (Thuja occidentalis L.; 11, 10, and 10 m²·ha⁻¹, respectively), but eastern white pine was less abundant in the mature stand. Snag basal area was 7 m²·ha⁻¹ in the old-growth and mature stands and was dominated by balsam fir and northern white-cedar. Total coarse woody debris (CWD) volumes were 145 and 83 m³·ha⁻¹ in the old-growth and mature stand, respectively. The decay class distribution in each area was skewed toward advanced decay classes. Most CWD was in the form of logs and snags in both areas, but snag volume in the old-growth area was approximately 3 times that in the mature stand (75 vs. 26 m³·ha⁻¹). In both stands, balsam fir and northern white-cedar each accounted for 21–30% of total CWD. Eastern white pine contributed 28% of the CWD in the old-growth area but was not present as CWD in the mature stand. Both forests are uneven-aged, with the earliest species establishing in the 1600s and 1750s for the old-growth and mature stands, respectively. No species exhibited major growth releases in the old-growth or mature stands, but several exhibited moderate releases. The age and diameter distributions of the old-growth area suggest that no stand-initializing disturbances have affected the forest for at least 250 years. Instead, fine-scale treefall gaps created by single or multiple treefalls are the dominant mode of regeneration in this forest.

Ehrenfeld, J. G. (Cook College, Rutgers University, New Brunswick, NJ 08901). Vegetation of forested wetlands in urban and suburban landscapes in New Jersey. J. Torrey Bot. Soc. 132: 262–279. 2005.—Forested wetlands in the northeastern US are increasingly surrounded by urban and suburban land-use, as development spreads outwards from city centers. I have studied a sample of 21 mature deciduous forested wetlands in a densely populated and long-settled region, northeastern New Jersey, in order to 1) describe characteristics of the plant communities of wetlands in such human-dominated landscapes, and 2) test the utility of hydrogeomorphic classification (HGM) in explaining the variation in composition and structure observed among the sites. The wetlands support a rich flora of over 300 species, with a mean richness of 66–92 species per site for the different HGM classes; common species were similar to those reported in previous studies of undisturbed red maple swamps. Structural characteristics (tree diameter and stem densities) were, like species richness and species composition, similar to those reported in previous reviews of red maple swamps, suggesting that despite the urban setting, community composition and structure of these wetlands are similar to those of undisturbed wetlands. Exotic species represented on average 5–11% of the flora of the sites, a value similar to other forested wetlands, suggesting that the urban setting does not result in a higher degree of exotic invasion than expected for forested wetlands in non-urban landscapes. HGM classification was poorly related to all aspects of vegetation structure, suggesting that at least in urban landscapes, it is not useful for predicting characteristics of the vegetation. The ability of these communities to resist major changes due to the urban setting may reflect the facultative-wetland status of most of the species; their ability to tolerate a wide range of wetland conditions allows them to persist despite alterations of hydrological regimes. Forested wetlands in developed landscapes can evidently maintain community composition and structure similar to those in undeveloped landscapes.

Webster, C. R. (School of Forest Resources and Environmental Science, Michigan Technological University, 1400 Townsend Drive, Houghton, MI 49931), M. A. Jenkins (Twin Creeks Natural Resources Center, 1314 Cherokee Orchard Road, Great Smoky Mountains National Park, Gatlinburg, TN 37738), and J. H. Rock (Twin Creeks Natural Resources Center, 1314 Cherokee Orchard Road, Great Smoky Mountains National Park, Gatlinburg, TN 37738). Twenty years of forest change in the woodlots of Cades Cove, Great Smoky Mountains National Park. J. Torrey Bot. Soc. 132: 280–292. 2005.—Changes in forest composition and structure were investigated by comparing two decades of permanent plot records (1977–1978 and 1995–2002) for the woodlots of Cades Cove, Great Smoky Mountains National Park, Tennessee. The importance of late-successional shade-tolerant species, such as Tsuga canadensis L. Carr. (eastern hemlock), increased in the understories and overstories of all of the forest types examined. The most significant increases were observed in the white pine-mesic oak and successional pine types. Our results suggest that most of the woodlots are currently undergoing stem exclusion with some stands in the early stages of understory reinitiation. The most pronounced structural changes were observed in the successional pine woodlots, which are experiencing rapid attrition of Pinus virginiana Mill. (Virginia pine), a short-lived pioneer species. Over the last two decades the diversity, richness, and density of woody understory vegetation in the woodlots has declined. These results are likely due to a combination of factors including natural stand developmental processes and the legacy of high white-tailed deer (Odocoileus virginianus Zimmerman) densities at Cades Cove.

Sherman, R. E., P. H. Martin, and T. J. Fahey (Department of Natural Resources, Cornell University, Ithaca, NY 14853) Vegetation-environment relationships in forest ecosystems of the Cordillera Central, Dominican Republic. J. Torrey. Bot. Soc. 132: 293–310. 2005.—We examined forest vegetation-environment relationships in the central mountain range of Hispaniola to improve general understanding of tropical montane forests. Forest inventory data were collected in 1999 and 2000 from 245 plots established in the Armando Bermúdez and Carmen Ramírez National Parks, Dominican Republic, over an elevation range of 1,100–3,075 m. Average tree density (≥ 10 cm dbh), basal area, and dbh were highly variable across the elevation gradient; species richness declined significantly with elevation; and the canopy height of broadleaved stands declined whereas the height of stands dominated by the endemic pine, Pinus occidentalis Sw., was relatively constant across the elevation gradient. Four major forest associations were identified using TWINSPAN: a low elevation broadleaved forest; a pine-broadleaved mixed forest; a mid-elevation cloud forest; and a largely monospecific pine forest that extends from the cloud forests to the summits of the highest peaks and dominates the leeward slopes of the mountains. Species composition varied continuously along the elevation gradient up to 2,250 m; however, above 2,250 m there was an abrupt shift from cloud forest to monospecific pine forests. Temperature, humidity, and fire history appear to regulate the position of this boundary, probably reflecting the position of the trade wind inversion. Ordination and logistic regression indicated that disturbance history and topo-edaphic factors influenced individual species distributions.

Schultz, G. P. (4327 Meridian Ave. N., Seattle, WA 98103). Vascular flora of the El Edén Ecological Reserve, Quintana Roo, Mexico. J. Torrey Bot. Soc. 132: 311–322. 2005.—The El Edén Ecological Reserve, Quintana Roo, Mexico, is a 1500 hectare privately owned reserve created in 1992 for research and conservation of the dry tropical forests in the northeastern Yucatán Peninsula. The reserve lies within a greater bioregion known as the Yalahau, which has been noted for its extensive wetlands, rare elsewhere in the Peninsula. The vegetation of the reserve represents all the major vegetation types of the greater bioregion and includes mature semideciduous dry tropical forest, various aged stands of successional forest, seasonally inundated forest and palm/cattail savanna as well as several permanent water bodies. The purpose of this study is to document the flora of the reserve. The vascular flora of the El Edén Reserve includes comprises 404 species, 306 genera and 99 families. Ferns (Division Pteridophyta) account for 8 species and 8 genera in 7 families. Cycads (Division Cycadophyta) account for one species in one family. Flowering plants (Division Magnoliophyta) account for 395 species in 297 genera and 91 families. Monocots (Class Liliopsida) account for 68 species in 51 genera and 18 families. Dicots (Class Magnoliopsida) account for 327 species in 246 genera and 73 families. Exotics only account for 3.5% of the flora, and plants with pantropical distribution (mostly weedy herbs) account for 6.3%. Yucatán Peninsula endemics account for 9.5% (39 species) of the total flora.

Leck, M. A. (Dept. Biol., Rider Univ., Lawrenceville, NJ 08648) and C. F. Leck (Dept. Ecol. & Evol. Biol., Cook College, Rutgers Univ., New Brunswick, NJ 08901). Vascular plants of a Delaware River tidal freshwater wetland and adjacent terrestrial areas: Seed bank and vegetation comparisons of reference and constructed marshes and annotated species list. J. Torrey Bot. Soc. 132: 323–354. 2005.—Constructed wetland soil samples contained many more species with densities > 100 seeds / m² than reference marsh ones (102 vs. 28); constructed wetland densities for many species were considerably higher and richness (species / sample) were > 2× greater than the reference marsh. Of the total 218 seed bank species, 60 were common to both and 34 occurred only in reference marsh samples. Numbers of cover species were similar, but composition differed. Invasive species, notably Lythrum salicaria, Phalaris arundinacea, and Phragmites australis, were more important in constructed wetland soil samples and vegetation. Non-native species comprised 9 % and 13 % of the reference marsh and constructed wetland seed bank species and 8 % and 12 % of the cover species, respectively. Variable dispersal patterns and in situ seed production contributed to these differences. Over the entire study area (wetlands and adjacent terrestrial areas) we recorded 875 species, representing 141 families, more than doubling the number observed in a 1988 report. The families having the most species were Asteraceae (103 species), Poaceae (100), and Cyperaceae (83). The largest genera were Carex (46) and Polygonum (19); seven other genera also had ≥ 10 species. Nine species were pseudo-viviparous, producing plantlets on inflorescences. Non-native species comprised 27 % of the total flora. Overall there were 37 NJ rare / endangered species for the entire area; 11 occurred only in the constructed wetland with constructed wetland soil samples containing more than the reference marsh samples (8 vs. 1). Available lists from 1824, 1887, and 1964/65 and five species known only from herbarium specimens indicate that several species have been extirpated since the 19^th C. Anthropogenic influences continue to have impact on diversity.

Maliti, C. M. (Department of Biology & Med. Lab. Technology, Bronx Comm. College, CUNY, University Avenue & West 181 Street, Bronx, NY 10453), D. V. Basile (Department of Biological Sciences, Lehman College, CUNY, Bronx, NY 10468), and W. A. Corpe (Department of Biological Sciences, Columbia University, New York, NY 10027). Effects of methylobacterium spp. strains on rice Oryza sativa callus induction, plantlet regeneration and seedlings growth in vitro. J. Torrey Bot. Soc. 132: 355–367. 2005.—Leaf surfaces of higher plants are colonized by diverse microorganisms. In the present study we report the isolation two strains of pink-pigmented methylotrophic bacteria (PPFM) designated Q4 & Q5. Both strains significantly stimulated growth and development of two rice cultivars, Japonica cv. CR76 and Indica cv. A301, cultured axenically on MS or B5 medium. Co-incubation of strains Q4 and Q5 with embryo-derived rice calli on B5 medium-devoid of exogenous phytohormones resulted in continued callus growth but inhibited plantlet regeneration. These results mimicked those produced by B5 medium supplemented with auxin and cytokinin. Co-culture of Q4 & Q5 as cobionts with 5 day old Japonica and Indica seedlings resulted in a significant (P ≤ 0.05) stimulation of four growth parameters; root development, stem growth, leaf development and biomass productivity, measured in 9 day growth period. The results of the in vitro experiments indicate that strain Q4 and /or Q5 inhabiting rice plant surfaces under cultivation could significantly stimulate the plants growth and development.