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ARS Home » Midwest Area » Morris, Minnesota » Soil Management Research » Research » Publications at this Location » Publication #88658


item Forcella, Frank

Submitted to: Northwest Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/15/1998
Publication Date: N/A
Citation: N/A

Interpretive Summary: Exotic plant species continue to be introduced into the United States. Some of these species establish so well that they spread and become problem weeds. Keeping track of which of the thousands of exotic species are spreading and causing problems is a difficult task. To help solve this problem a computer software application was developed. The software is known as INVADERS. This software stores data for the known distributions and time of detection of more than 3,000 plant species in the states of Idaho, Montana, Oregon, Washington, and Wyoming, that is, the "Northwest." INVADERS was used to search for exotic species that were introduced in the Northwest since 1950. The search resulted in nearly 300 species, of which 134 were judged to have a high potential to establish and become problems. Of these species, five appear to merit special attention. Some of these species do not yet have common names in the U.S. lexicon. Possible common names (and Latin names) of these five species are: white bryony, yellow hawkweed, Indian Balsam, Japanese knotweed, and stalk-seed weed (Bryonia alba, Hieracium pratense, Impatiens glandulifera, Polygonum cuspidatum, and Scorzonera lacinata, respectively). Use of the software, INVADERS, will enable close observation of these species and many others so that quarantine and control measures can be implemented quickly if necessary.

Technical Abstract: Non-native plant species continue to be introduced into North America both accidentally and intentionally for horticultural and agricultural purposes. Some of the new species will spread extensively and some likely will become weeds of importance. We used a floristic database (INVADERS) to examine the status of incipient plant invasions in northwest United States (Washington, Oregon, Idaho, Montana and Wyoming). We queried INVADERS for distribution records of plant species exotic to North America that were first recorded in the northwest states on or before 1950. The query resulted in 292 species, of which 134 were judged to have become established or to have high potential for establishment beyond artificial environments such as lawns and gardens. Inherent potential for successful naturalization was based on examination of several invasive plant lists and the international literature on plant invasions. Thirty species have become fairly widespread in the five-state northwest region (reported from >five counties), and several are known to be aggressive invaders in other regions of North America or in other parts of the world. Five species discussed in the text are notable for rapid spread and/or indications of aggressiveness: Polygonum cuspidatum (syn: Fallopia japonica, Reynoutria japonica), Bryonia alba, Impatiens glandulifera, Hieracium pratense and Scorzonera laciniata. Compared with the early exotics (mid 1800s - early 1900s) which tended to be annual herbs, the post-1950 exotic flora shows a trend toward greater proportions of perennials and woody growth forms (shrubs and trees). Some applications of floristic databanks in regional-scale management of plant invasions are discussed.