Previous research on #3 nursery container-grown shrubs suggests that some common shrub species could be established in the Florida landscape under natural rainfall when irrigated with 3 L of water every 4 days in U.S. Department of Agriculture hardiness zones 8b and 9a or every 2 days in zone 10b until first roots reached the canopy edge (≈20 weeks after planting). The current study evaluated the effects of these irrigation frequency recommendations on plant vigor, canopy growth, root growth, and aesthetic quality of 21 common landscape shrub species (10 Florida native and 11 non-native) planted in Florida in zones 8b, 9a, or 10b. Data suggests that it may be appropriate to adopt the 20-week low-volume irrigation recommendations for the establishment of a wide variety of container-grown Florida native and non-native shrubs. However, Florida native and non-native shrubs should be monitored for symptoms of drought stress for 2 years after planting.
A.L. Shober, K.A. Moore, C. Wiese, S.M. Scheiber, E.F. Gilman, and M. Paz
Sloane M. Scheiber, Richard C. Beeson, and Heather Bass
Native plants are often promoted as an approach for water conservation in urban landscapes. However, information regarding plant water needs is based primarily upon anecdotal observations of plant performance. Direct comparisons between native and introduced species using physiological measures of plant water stress are unavailable to support or refute such recommendations. Ligustrum japonicum and Myrica cerifera, representing an introduced and native species, respectively, were transplanted into a fine sand soil to evaluate establishment rates and growth characteristics under two irrigation regimes. Each species was irrigated either daily or every 3 days and received 1.3 cm of irrigation per event for 8 months after transplant. Predawn, midday, and dusk water potentials were recorded on three consecutive days monthly, with cumulative stress intervals calculated. Height, growth indices, shoot dry mass, root dry mass and leaf area were also recorded. Water potential was significantly influenced by day of water stress level. On days without irrigation, water stress was generally greater and affected growth. Myrica irrigated daily had the greatest growth, yet plants receiving irrigation every 3 days had the least growth and greater leaf drop. In contrast, for Ligustrum there were no differences between irrigation regimes in growth responses except for growth index.
Sharon Frey and Carolyn Robinson
Plants have been introduced into the United States intentionally as well as unintentionally as seeds and weeds. Technological advances, a mobile society, and our curiosity and desire to improve our landscapes have led to an ever-increasing invasive movement. These alien plants can jeopardize native populations, alter ecosystems, alter fire and water regimes, change the nutrient status, modify habitats, and cause significant economic harm. Today's public is unaware of the danger some non-native plants species pose to natural areas, thereby contributing to the lack of control for non-native invasive plants. This study looked at the knowledge and attitudes of Texas Master Gardeners as related to invasive species commonly used in landscaping. A web survey was made available to all Texas Master Gardeners that included pictures of plants along with their common and scientific names. Participants were asked to identify which they thought were invasive and contribute information regarding their knowledge of non-native invasive plants. Each of the invasive plants shown is on both the federal and the Texas Invasive Plant lists. Inquires were made concerning the occurrence of these plants in the participants' personal landscape and communities and their perceptions of each plant as an invasive threat. The purpose of the study is to determine if a relationship exists between knowledge, attitudes and perceptions of the participant and the occurrence of non-native invasive plants in the landscape. The results of this study will help determine factors that contribute to the lack of control for non-native invasive plants.
D. L. Creech and J. Singhurst
The Stephen F. Austin State University Arboretum occupies ten acres of campus property on the banks of LaNana creek, the stream that bisects the campus and the city of Nacogdoches, the oldest town in Texas. The mission statement of the Arboretum is to promote the conservation, selection and use of the native plants of east Texas. There are 19 species in east Texas that are either federally endangered, state endangered, or in danger of extirpation from the state. Many others face a serious decline in numbers as appropriate habitats diminish. A long-term project of ex situ and in situ conservation was initiated in 1992. Goals include: 1) acquire global position and vegetative analyses of endangered plant communities, 2) utilize ArcCAD® (a PC-GIS software) to archive a collection of maps, photographs, plant community data, and text, 3) maintain an ex situ collection of endangered plants from known provenances in the arboretum, and 4) reintroduction of species into appropriate protected habitats. The project involves the cooperation of several state and federal agencies and integrates the resources of a university horticulture program with the needs of endangered plant conservation.
Anne M. Hanchek
Why do people visit the grounds of a botanical garden or arboretum? What draws them to that “experience of nature”? What can we do as horticulturists, landscape architects, and educators to make garden areas more appealing and fulfilling to visitors? The Prairie Interpretive Committee of the Minnesota Landscape Arboretum asked these questions in 1991 as it convened to analyze the current and future status of the Arboretum's Bennett/Johnson Prairie. To understand visitor usage and needs, Arboretum members were surveyed about frequency of visits, reasons for visiting, specific visitor services, and suggestions for improvements. Among the 151 responses, the major reasons for visiting were the pleasures of walking, observing, and being at peace. “Open”, “wild,” and “natural” were common key words. There was keen interest in native plants and their historical role as well. Sitting areas, maps, path markers, plant labels, and self-guided tours were the primary requests for improvement. A high percentage found the demonstration area interesting and useful. The Interpretive Committee used this research to guide the landscape architect, create a brochure, and develop an integrative master plan for the prairie area.
Tera M. Bonney, Shawn P. Brown, Snake C. Jones, Kirk W. Pomper, and Robert L. Geneve
The pawpaw [Asimina triloba (L.) Dunal] is a native plant found mainly in the southeastern and eastern United States, and its fruit has great potential as a new high-value crop in these regions. Although there are ≈45 named pawpaw cultivars, breeding for improvement of specific traits, such as fruit size and quality, is desirable. Our long-term goal is to utilize molecular marker systems to identify markers that can be used for germplasm diversity analyses and for the construction of a molecular genetic map, where markers are correlated with desirable pawpaw traits. The objective of this study was to identify random amplified polymorphic DNA (RAPD) markers that segregate in a simple Mendelian fashion in a controlled A. triloba cross. DNA was extracted from young leaves collected from field-planted parents and 20 progeny of the cross 1-7 × 2-54. The DNA extraction method used gave acceptable yields of ≈7 μg·g-1 of leaf tissue. Additionally, sample 260/280 ratios were ≈1.4, which indicated that the DNA was of high enough purity to be subjected to the RAPD methodology. Screening of 10-base oligonucleotide RAPD primers with template DNA from the parents and progeny of the cross has begun. We have identified two markers using Operon primer B-07 at 1.1 and 0.9 kb that segregate in a simple Mendelian fashion in progeny of the 1-7 × 2-54 cross. Other primers and controlled crosses will also be screened.
The mission of the SFASU Arboretum is to promote the conservation, selection, and use of the native plants of Texas and to encourage diversity in the urban landscape philosophy of the region. A decade since its inception, the 10-acre arboretum features many uncommon, unusual, and difficult-to-find species and cultivars, many deserving greater use in the region. The living collection has been acquired through botanical gardens, arboretums, private collections, the nursery industry, and expeditions. The list of promising plants that have surfaced includes many that are not easily available in the trade. The issues involved in woody and herbaceous plant evaluation include computer mapping and record keeping constraints, the long-time frame for evaluation with many woody plants, and difficulties in propagation. The arboretums's plant acquisition policy and record keeping and computer mapping system is currently tracking more than 2500 taxa in the living collection. An overview of the first decade of plant performance and a strategic plan for acquisition, propagation, evaluation, distribution, and promotion are presented.
Jyotsna Sharma and Jim Rich
Plants infected with Meloidogyne spp. (root-knot nematodes) often are stunted and lose aesthetic value due to chlorosis, wilting, and leaf margin necrosis. We assessed reproduction of three root-knot nematode species, Meloidogyne arenaria, M. incognita, and M. javanica, on five plant taxa native to the southeastern U.S. The plant taxa included were: Hydrangea quercifolia `Oakleaf', Viburnum obovatum `Densa', Itea virginica `Little Henry', Illicium parviflorum, and Clethra alnifolia `Ruby Spice'. Three commonly grown non-native shrubs, Ligustrum japonicum `Texanum', Ilexcrenata `Compacta', and Buxus microphylla `Wintergem', also were included in the study to serve as susceptible, positive controls. Highest gall rating (10) was observed on roots of I. crenata `Compacta' infected with M. incognita, but highest number of eggs (6397 eggs/g of roots) was observed in plants of this cultivar inoculated with M. javanica. Few or no galls were observed on roots of the five native plant taxa, and nematode eggs were recovered only from roots of I. virginica `Little Henry' inoculated with M. arenaria and M. javanica (13 and 20 eggs/g of roots, respectively). Fresh weights of shoots or roots were not affected by nematode inoculation. Due to lack of root gall development and little or no reproduction on the native taxa, we conclude that these are resistant or immune to the three species of Meloidogyne and might be suitable for planting in infested soil.
Renee Keydoszius and Mary Haque
During the fall semester of 2003, a Clemson University introductory landscape design class collaborated with South Carolina Botanical Gardens staff and coordinators of Sprouting Wings, an after school gardening program for at risk children, to design an exploratory Children's Garden within the Botanical Gardens. Project methodology included site selection, research, site analysis, conceptual diagrams, preliminary designs, and full color renderings of final designs. Students periodically presented their progress on the project to the clients in order to receive feedback and advice. One of the thirteen themed gardens designed is the Wonders of Water Garden. Project goals were to create a center for environmental education addressing current issues in water quality such as pollution from industries and runoff, erosion, stream degradation, and sedimentation resulting from land clearing and development. Visitors will be able to observe and learn about various environmental factors affecting native plant and animal life. The garden will help to teach environmental stewardship and understanding of general aquatic ecology. An observation deck, serpentine bridge through a bog garden, and a bridge crossing a waterfall stream will allow close observation of native aquatic plant and animal life. The Wonders of Water Garden design includes the bog garden and carnivorous garden that border two pools connected by a stream of small waterfalls which may be used to create awareness of current water quality issues and serve as a model to teach visitors the importance of water and aquatic plants in the environment.
I. Nadeau, H. Desilets, S. Gagne, S. Parent, P. Moutoglis, and D. Robitaille
American ginseng (Panax quinquefolius) is a native plant of the deciduous forests of eastern North America. This highly valuable medicinal plant has been grown commercially for nearly a century in the field, under artificial shade sources, or in forests under mature trees. Wood-grown ginseng roots are highly similar to the wild ones, which increases their value. However, the time required to produce a marketable root is two to three times longer in the forest than in the field. In an attempt to reduce this time, a new technique has been developed to produce ginseng transplants destined for forest culture. Ginseng seedlings pre-treated with giberellic acid were sown in forest plots in a peat base culture medium ammended with an inoculum of the arbuscular fungi Glomus intraradices or G. etunicatum. The plantlets were grown for 18 weeks in greenhouse under shade cloth. The two Glomus spp. suceeded in colonizing the ginseng rootlets, developing the `Paris' mycorrhizal type, as previously reported for this plant. In addition, plantlets inoculated with G. etunicatum weighed 15% more than the control and were significantly more branched. The amount of P, K, and Mg in the roots was significantly higher in mycorrhizal ginseng plantlets.