The relationship was analyzed between historical annual rainfall and pecan [Carya illinoinensis (Wangenh.) K. Koch] homogeneity in selected hardwood populations along two river systems in the native habitat of the species. Tree species other than pecan (sympatric species) were more abundant with increasing rainfall in that the more homogenous pecan populations were located in geographic areas with the least rainfall. These results are the first to establish that pecan stand homogeneity across geographic areas is inversely related to the amount of annual rainfall. Variation in soil texture within geographic areas was also strongly correlated with variation in pecan homogeneity and pecan density. Pecans occur principally on loamy bottom lands and grow on clayey bottom lands in less abundance. A hypothesis related to growth partitioning between root and shoot is proposed to account for pecan's survival advantage, and thus higher stand homogeneity, with decreasing rainfall in native pecan areas. Conversely, the decrease in stand homogeneity with increasing rainfall is proposed to be due to increased forestation of sympatric species on clayey sites that are not optimum for pecan. Across the rainfall gradients, pecan's shade intolerance is suggested to be minimized by differential site requirements for pecan and its sympatric species.
Dale T. Lindgren
Wildflowers/native plants are increasingly being used in landscapes, especially in low maintenance areas. Buffalograss is also receiving attention as a low maintenance grass. Establishing wildflowers in buffalograss would be useful in sites where mowing occurred only once in the fall, such as with minimeadows. Four experiments were conducted to study the establishment of wildflowers in buffalograss. Survival of wildflowers after one year was 88% when wildflowers were planted as greenhouse grown transplants and buffalograss plugged in 2 weeks later, 67% when one-year-old field grown wildflowers were transplanted into buffalograss plugged at the same time and 48% when greenhouse grown wildflowers were transplanted into established buffalograss. Establishment of wildflowers overseeded into established buffalograss sod was very low. There were significant differences in wildflower survival within each study. Species which performed well in buffalograss included Leadplant, Blue Fax, Purple Prairie Clover, Little Bluestem and Stiff Goldenrod.
Erika N. Kocsis, Ronald F. Hooks, and James N. McCrimmon
The use of grasses native to New Mexico are preferred for revegetating Albuquerque's sewage sludge disposal site. A greenhouse study was conducted to determine the most appropriate grass species that could be used in revegetation. Nine grasses grown in soil collected at Albuquerque's sludge disposal site were compared based on germination measurements, including plant height and density. Final shoot and root weights also were taken for comparison. Plant tissue was analyzed for the accumulation of metals and salts. With 200 ml of water applied weekly, plant height was greatest in spike dropseed (Sporobolus contractus A. S. Hitchc.) at 33.86 cm; plant density was greatest in alkali sacaton (Sporobolus airoides Torr.). Results indicate the grasses that have the best potential for use in revegetation are blue grama [Bouteloua gracilis (H.B.K.) Lag. ex Griffiths], sideoats grama [Bouteloua curtipendula (Michx.) Torr.], and alkali sacaton.
The author investigated, recorded, observed and analyzed the major wildflowers in Mount Huangshan---the natural and cultural heritages listed by the ESC0 of UN for the first time. On the basis of their desirable characteristics, more than 300 wild ornamental species are divided into 8 categories -–-historical old trees, rare and endangered species, evergreen ornamentals, blooming trees and shrubs, plants with colored foliage and fruit in fall, vines, herbaceous ornamentals and ground covers, and ornamental ferns. Mount Huangshan is one of the richest regions of native ornamentals in Eastern China and the most famous natural beauty in Pan-China. There are about 1500 wild landscape plants in and around it. Finally the paper puts forth some proposals and methods for introduction and utilization of wild ornamental plants. That is, investigation, classification,acclimatization and cultivation of them, and building a sort-out botanical garden for the germplasmic preservation and the flourishing landscape tourism.
Norman E. Pellett, Nancy Rowan, and John Aleong
Flower buds of eight ecotypes representing three native North American azalea species being grown in Burlington, Vermont were compared for cold hardiness by laboratory freezing during the cold acclimation period for three years. Species were Rhododendron calendulaceum, R. prinophyllum, and R. viscosum. There was a high variation in the number of florets killed within an inflorescens in response to freezing temperatures. There was little difference in the cold hardiness of florets of R. Pinophyllum and R. calendulaceum florets, but R. viscosum florets were hardier. Some differences were noted in cold hardiness of florets of ecotypes, but these were not necessarily related to latitude of origin. Cold hardiness showed a relationship with the daily mean temperature of the three days preceding freezing tests.
D.L. Creech and D. McDonald
Texas is botanically diverse with approximately 5500 native plants identified: east Texas contains about 40% of the total. While most species are stable, many are classified as rare, threatened, vulnerable, or endangered. Databases for east Texas plant communities and vegetative analyses are numerous. However, they are not yet integrated into easy-to-sort-and-query computer files. Computer-Assisted Drafting (CAD) and Geographic Information Systems (GIS) technology offers powerful applications to the storage, management, and spatial analysis of species inventories, plant community dynamics, and long-term habitat monitoring. At SFASU, the College of Forestry's GIS Center is being utilized to develop comprehensive east Texas resource inventories on a ten-station HP Apollo/ArcInfo platform. In the horticulture program, a twenty-station PC/AutoCad teaching laboratory is being used to create layered maps of the SFASU Arboretum, the on-campus landscape and off-campus plant communities. The integration of CAD and GIS projects through a DXF format takes advantage of the attributes of both technologies.
Jason Singhurst, D. L. Creech, and J. Williams
In Texas, 5,500 native species are distributed over an area comprised of ten regional habitat types. In the Piney Woods region of east Texas, 2,300 plant species occupy 15 million acres. In east Texas, the USFWS has identified 4 species that are federally endangered and 15 that are candidates for that listing. Interest in protecting rare plant habitats and reintroducing those species into similar and appropriate ecosystem types has led to new tools in research and development. Remote sensing is one; this technology is used to derive information about the earth's land and water areas from images acquired at a distance Multispectral and spatial techniques are applied to process and interpret remote sensing imagery for the purpose of producing conventional maps, thematic maps, reource surveys, etc., in the fields of agriculture, botany, archeology, forestry, geography, geology. and others. Remote sensing is used to classify vegetation, interpret forest photogrammetry, estimate timber production, and identify crops, individual plants and leaf structure. This specific project was initiated to determine the potential of remote sensing as a tool to locate known and new rare plant communities in east Texas. To develop benchmark data, a Daedalus scanner image of a previously surveyed and AutoCAD® mapped area, the Vista forest on the SFASU campus, was utilized to develop correlations between imagery, vegetation types and species. By inserting various scan images under the Vista forest AutoCAD® map, known tree species were analyzed through their specific spectral emission characteristics across nine bands. This pilot project has indicated that it is simple to separate pines from hardwoods and illustrate major land use features. However, separation at the species level or groups of species has not been achieved. This paper will trace the history of this project, describe problems and obstacles encountered, and make recommendations for future strategies.
E.T. Pippin, E.W. Bush, D.J. Lee, and R.E. Strahan
Weeping lovegrass (Eragrostis curvula) is commonly used in native areas bordering golf courses in the Southeastern United States. These areas do not receive significant levels of maintenance, thus weed encroachment is a problem that can negatively impact the functional and aesthetic values of the golf course. The objectives of this study is to determine which selective postemergent herbicides labeled for use on golf courses can remove weeds from Weeping Lovegrass and to determine the level of phytotoxicity. Herbicides included monosodium methane arsenate (MSMA 6.0) applied at 3.0 lb/acre a.i., sulfosulfuron (Certainty) at 0.047 lb/acre a.i., metribuzin (Sencor 75 DF) at 0.5 lb/acre a.i., and imazaquin (Image 70 DG) at a rate of 0.5 lb/acre a.i.. Treatments were applied on July 20, 2004 to 9.6 × 9.6 plots arranged in a randomized complete block design (RCBD) using Teejet 8005 nozzles at 40 psi calibrated to deliver 40 ga/acre. Plots were monitored daily and data was collected 0, 7, 14, 21, 28, 35, and 42 DAT. Sulfosulfuron and MSMA provided the highest level of weed control 35 DAT. Metribuzin and imazaquin provided limited weed suppression compared to the control. Initial phytotoxic damage to the Lovegrass was observed in all herbicide treatments. The highest level of phytotoxic damage was observed in the MSMA and Metribuzin treatments; however there was no apparent damage at 42 DAT. Herbicide applications of sulfosulfuron and MSMA are effective in reducing weed populations with acceptable levels of phytotoxicity to the Lovegrass.
Douglas S. Chapman and Robert M. Augé
Understanding physiological drought resistance mechanisms in ornamentals may help growers and landscapers minimize plant water stress after wholesale production. We characterized the drought resistance of four potted, native, ornamental perennials: purple coneflower [Echinacea purpurea (L.) Moench], orange coneflower [Rudbeckia fulgida var. Sullivantii (Beadle & Boynt.) Cronq.], beebalm (Monarda didyma L.), and swamp sunflower (Helianthus angustifolius L.). We measured a) stomatal conductance of leaves of drying plants, b) lethal water potential and relative water content, and c) leaf osmotic adjustment during the lethal drying period. Maintenance of stomatal opening as leaves dry, low lethal water status values, and ability to osmotically adjust indicate relative drought tolerance, with the reverse indicating drought avoidance. Echinacea purpurea had low leaf water potential (ψL) and relative water content (RWC) at stomatal closure and low lethal ψL and RWC, results indicating high dehydration tolerance, relative to the other three species. Rudbeckia fulgida var. Sullivantii had a similar low ψL at stomatal closure and low lethal ψL and displayed relatively large osmotic adjustment. Monarda didyma had the highest ψL and RWC at stomatal closure and an intermediate lethal ψL, yet displayed a relatively large osmotic adjustment. Helianthus angustifolius became desiccated more rapidly than the other species, despite having a high ψL at stomatal closure; it had a high lethal ψL and displayed very little osmotic adjustment, results indicating relatively low dehydration tolerance. Despite differences in stomatal sensitivity, dehydration tolerance, and osmotic adjustment, all four perennials fall predominantly in the drought-avoidance category, relative to the dehydration tolerance previously reported for a wide range of plant species.
Usha Rani Palaniswamy
Taiwanese Native Medicinal Plants: Phyto-pharmacology and Therapeutic Values. Thomas S.C. Li. 2006. CRC Taylor & Francis. 379 p. $189.95, hardcover. ISBN 0-8493-9249-7. The publication is educational in its presentation of the medicinal