Introduction

Non-native plants are those that have been introduced to a location(s) outside their native or natural range. Generally, these plants were introduced from another continent or region, ecosystem or habitat within an ecosystem (Swearingen 2004). These introductions have been either purposeful or accidental. Many non-native plants have been introduced into new areas because they are beneficial plants that are used in agriculture and horticulture, thus are depended upon for food, fiber and aesthetic reasons. Other non-native plants can become problematic.

Non-native plants are virtually everywhere. These plants (also known as introduced, non-indigenous, alien, or exotic) are found in many different urban and rural settings. In urban environments, non-native plants are found in residential and commercial landscapes, recreation areas (parks, open spaces and play fields), flower and vegetable gardens, sidewalk cracks, and along transportation corridors (roads, highways, railways, trails). In rural environments, non-native plants can be found in agricultural fields, irrigation ditches, and in natural areas (deserts, rangelands, forests, meadows, etc.). These plants now can be found in virtually every terrestrial and aquatic environment.

Introductions of non-native plants that are unintentional occur when reproductive plant parts hitch rides on cargo ships and watercraft, vehicles and aircraft in packing material or ballast water, or on equipment or animals. Once they arrive in a new location, they spread, especially through roadways or migration corridors, and by wind or water.

Many non-native plants arrive in new environments and disappear shortly after their arrival, unable to tolerate the new environmental conditions. Many of these need human assistance to survive and propagate with special planting, watering and fertilization needs. Some become established, and spread into new areas when favorable conditions occur. There are many non-native plants, however, that become established, spread quickly and easily and are aggressive in nature. The latter are referred to as exotic invaders (D’Antonio and Haubensak 1998).

Non-native exotic invaders are usually very difficult to control. Substantial attention has been given to these plants because their impacts are far reaching and potentially harmful. Invasive plants are defined as those that are non-native to the ecosystem under consideration, and their introduction causes or is likely to cause economic or environmental harm, or harm to human health (Executive Order 13112).

Non-native exotic invaders usually exhibit the following characteristics:

1. They display rapid growth and spread quickly.
2. They establish over large areas.
3. They persist in new environments.

Owners and managers of land and waterbodies are especially concerned about invasive plants. Because they are very difficult to control, their management often requires a combination of methods and tools to be effective. Often management costs are high and several years of continual commitment are required to control or eradicate these plants.

Non-native invasive plants are extremely destructive and costly. They impact many environmental values such as the beauty of an area, wildlife habitat, native ecosystem structure and function. They compete with native plants; use precious soil and water resources; can be toxic or injurious to humans, pets and livestock; affect pollinators; and diminish recreational values.

The following is a checklist of the non-native plants that have been documented in southern Nevada (i.e., Clark, Lincoln and Nye counties). The list includes beneficial, naturalized, nuisance, or exotic invaders.

References

Brooks, M. and T. Esque. 2002. Alien Plants and Fire in Desert Tortoise (Gopherus agassizzi), Habitat of the Mojave and Colorado Deserts. Chelonian Conserv. Biol. 4(2).

Cronquist, A., A. H. Holmgren, N. H. Holmgren, J. L. Reveal, P. A. Holmgren. 1994. Intermountain Flora - Vascular Plants of the Intermountain West, U.S.A. New York Botantical Garden, NY.

DiAntonio, C. M. and K. Haubersak. 1998. Community and Ecosystem Impacts of Introduced Species. Fremontia 26(4).

Executive Order 13112 of February 3, 1999 - Invasive Species. Fed. Reg.: February 8, 1999 (Vol. 64 No. 25).

Hickman, James, ed. The Jepson Manual - Higher Plants of California. 1996. University of California Press. Berkeley, CA.

Nevada Plant List. 1998. Natural Resources Conservation Service. U.S. Department of Agriculture.

Powell, E. 2001. Checklist of Vascular Plants of Lake Mead National Recreation Area. National Park Service.

Swearinger, J. M. 2004. What the Heck Is an Invasive Plant? National Park Service, National Capital Region, Center for Urban Ecology.

Published by: Ryan, M. and M.L., Robinson, 2005, Checklist of the Non-native Plants of Southern Nevada, Extension | University of Nevada, Reno, SP-05-05

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