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.
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
Over the past 10 to 20 years, production of prevariety germplasm of native wildflower seeds has risen dramatically in response to the demand for site- or regionally specific ecotype seeds for roadside plantings as well as for ecological restoration
Potatoes are native to the Americas, concentrated in the western mountains extending from southern Chile to southern Utah and Colorado in the United States. The authors here describe their efforts to collect and study populations of the two wild
character in urban areas, several researchers have turned their interest in native Mediterranean perennials, mostly xerophytes, capable of growing on extensive green roofs ( Benvenuti and Bacci, 2010 ; Kotsiris et al., 2012 ; Nektarios et al., 2011
soil or root ball on establishment and growth of two native shrub taxa. MATERIALS AND METHODS Plant taxa used in this experiment included Rhododendron austrinum Rehd. (Florida flame azalea) and Itea virginica L. ‘Henry's Garnet’ (‘Henry's Garnet
In recent years the use of native plant materials for conservation and revegetation projects has received increased awareness and interest. The National Plant Materials Center (NPMC), in cooperation with the USDI-National Park Service, is involved in the revegetation of disturbed areas within our National Parks using native herbaceous and woody plants. This involves the collection of germplasm from selected niches within the Parks, an increase in seed and production of transplants, and reestablishment of native communities in natural areas.
One major focus of the program is to develop technology for improving native plant propagation and production, which should make the use of native plants more viable in the commercial sector. Germination of species of Tridens, Dichanthelium, Danthonia, Helianthus, Schizachyrium, and Andropogon has been improved to 80-95% by altering the germination environment. Production of these species in plugs has also been streamlined to maximize space efficiency and provide cost-effective methods for planting native grasses and wildflowers.
should be taken under consideration before applying green roof systems in Mediterranean regions are water availability, particularly in those areas with semiarid climate, biodiversity, and local character preservation. The use of native xerophytes in
Ten plant species native to southeast Alaska and surrounding regions were selected based on their value as ornamentals, food crops, disturbed site revegetation, and traditional Native American uses. Between 2003–05, seeds, cuttings, rhizomes, and bulbs from the 10 native plant species were collected in Sitka, Alaska, and propagated according to existing plant propagation protocol for each species. The most successful propagation method for each species was determined from field trials. This information was provided through workshops and Extension publications to gardeners in southeast Alaska and other parts of Alaska. The purpose of this project was to enhance growing local native plants as ornamentals, food crops, in disturbed site revegetation and for traditional Native American uses, particularly among native elders unable to collect these plants in the wild. A secondary purpose was to create a market for native plants in southeast Alaska and spawn a cadre of local cottage market gardeners to grow native plants for existing small nurseries. The 10 species selected included: Cornus canadensis, C. stolonifera, Empetrum nigrum, Fritillaria camschatcensis, Linnaea borealis, Oplopanax horridus, Rubus chamaemorus, Vaccinium parvifolium, Vaccinium ovalifolium, and Viburnum edule.
Oenothera biennis, common evening primrose, is grown commercially for its seed, which contains high levels of gamma-linolenic acid (GLA), a fatty acid with pharmaceutical and dietary importance. Other native species of Oenothera are being evaluated for the presence of GLA in their seed and their potential as a commercial source of GLA. Native evening primrose species have shown slow emergence and low germination percentages. Studies were conducted to determine the effects of chilling, scarification, and priming on germination of seed for six species of native evening primrose. Overall, seed germination was improved by seed treatments. However, responses to the various treatments differed among species.