Broadleaf arrowhead (Sagittaria latifolia Willd. [Alismataceae]), an obligate wetland species found from southern Canada and to northern and western South America, the West Indies, and Hawai'i (Hitchcock and others 2001), may be propagated reliably using seeds or tubers. This species provides both food and cover for many species of birds, mammals, fish, and aquatic insects (Thunhorst 1993). I describe both methods of propagation as they are used by the nursery staff of Environmental Concern, a nonprofit organization on the Eastern Shore of Maryland, to grow this species for use in wetland restoration and construction projects.
Success in rooting cold-hardy Arctostaphylos Adans. [Ericaceae] cuttings in Colorado is measured by particular attention to harvest timing, cutting preparation, sanitation, and media characteristics. Propagation methods used in Colorado piggyback on those used elsewhere and serve to simplify sometimes complex, if not unsuccessful, procedures. The vegetative propagation techniques and materials presented here should enable propagators to successfully root cold-hardy Arctostaphylos in high numbers.
Imazapic applied at 105 g active ingredient (ai)/ha (1.5 oz ai/ac) eliminated nonnative annual forbs for a single growing season and significantly reduced the production of a nonnative annual grass, cheatgrass (Bromus tectorum L. [Poaceae]), for 2 growing seasons following treatment, without negatively affecting native plant species in a northern Nevada fuelbreak. Imazapic may prove useful in maintaining fuelbreaks created in Wyoming big sagebrush (Artemisia tridentata Nutt. ssp. wyomingensis Beetle & Young [Asteraceae]) plant communities by controlling flammable nonnative annual weeds, not harming desirable native plants, and possibly assisting in the establishment of seeded fire-resistant plant materials.
Invasive exotic plants are displacing native plants and rapidly degrading native ecosystems. In this paper, we chronicle the sometimes erratic invasion biology of woody plants and review control strategies for some of the most serious woody invaders of eastern forests. Design features of a well-integrated control strategy include early detection, rapid response with the most effective control techniques possible, persistence and continued monitoring, and outreach/education to reduce the number of source populations on neighboring lands. Invasive plants are probably here to stay, but through concerted and diligent effort their spread and impact can be greatly reduced.
At Purdue University we are investigating ways to control invasive woody species growing in oak (Quercus L. [Fagaceae]) forests and other natural areas of Indiana. We have found several herbicides, and combinations of herbicides, that provide excellent control for a variety of woody invasive plant species when applied before, after, or in combination with mechanical removal. These control techniques offer a range of control options that are designed to be included in land managers' integrated vegetation management (IVM) plans. Vegetation management that integrates the control and replacement of invasive plants with the establishment of favorable vegetation can help managers to efficiently achieve habitat management objectives and avoid future invasive plant problems. Natural resource managers may find these suggestions and experiences useful when developing their own IVM plans.
Colorado blue columbine (Aquilegia caerulea James [Ranun-culaceae]), Palmer's penstemon (Penstemon palmeri Gray [Scrophulariaceae]), and Russian sage (Perovskia atriplicifolia Benth. [Lamiaceae]) were treated with 5 rates of a standard water-soluble fertilizer (0, 50, 100, 200, 400 mg/l [ppm] nitrogen [N]) to determine the optimum concentration for the production of plants in greenhouse containers. Plant quality and shoot dry matter increased while root:shoot dry matter decreased linearly with fertilizer concentration up to 200 ppm N for all species in a spring trial. Responses to fertilizer concentrations up to 400 ppm were less consistent in a fall trial. The response of gooseberryleaf globemallow (Sphaeral-cea grossulariifolia (Hook. & Arn.) Rydb. [Malvaceae]) and Rocky Mountain penstemon (Penstemon strictus Benth. [Scro-phulariaceae]) to 5 media pHs (average 4.5, 5.4, 6.0, 6.9, and 8.3) was also evaluated. During the summer and, for P. strictus, spring, plants growing in the lowest pH did not perform as well as in the intermediate pH treatments. Plant performance in the high pH treatment was consistently lower than in the intermediate pHs for both species at all times. Overall, results indicate these native species can be grown using fertilizer concentrations (200 ppm) and media pHs (5.1 to 7.2) similar to other common greenhouse plants.
We grow Zamia pumila L. (Zamiaceae), the only cycad occurring north of Mexico, using a low-tech but effective system. After collecting seeds from cones during winter, we simply scatter seeds onto outdoor germination beds composed of growing medium recycled from our container operation. After the first and second year of field bed germination, emergents are transplanted into containers. Finished container stock takes 3 to 5 y depending on desired size.