In the 2012 President's Budget Request, the National Biological Information Infrastructure (NBII) is terminated. As a result, all resources, databases, tools, and applications within this web site will be removed on January 15, 2012. For more information, please refer to the NBII Program Termination page.
With enormous environmental, economic, and health costs, invasive species are second only to habitat destruction as a cause of global biodiversity loss.
Invasive Species of the Week (IUCN Invasive Species Specialist Group - ISSG)
Click on the button below to open a PDF file of a fact sheet for the 'Invasive Species of the Week'.
The ISSG has launched this 'Invasive Species of the Week' button to raise awareness of the impacts of invasive species on native biodiversity and threatened ecosystems. For information about how to add this button to your own Web site, contact Shyama Pagad (Manager, Species Information Services, IUCN SSC ISSG).
Invasive Species
Image: Tamarisk (Tamarix spp.) infestation, Gila River, Arizona [Photo: Patrick Shafroth, USGS Fort Collins Science Center]
Each year numerous plant and animal species disperse from their natural range to new locations around the world. Many of these non-native, exotic species have colonized the Southwest region of the United States and become invasive, displacing native plant and animal ecological communities. The consequences of these invasions may be localized or widespread and impacts can range from minor to severe. Invasive species compete with native species, alter ecosystems, and may bring disease not only to native flora and fauna but to humans as well. Many federal, state, tribal, and local governments as well as non-governmental organizations are working to address this issue.
The Southwest Exotic Plant Information Clearinghouse (SWEPIC) is a cooperative effort among the U.S. Geological Survey, the National Park Service and Northern Arizona University to organize comprehensive information on exotic plant species in the Southwest into one web location. The SWEPIC assists all people and organizations committed to protecting the ecological and economic values of Southwest resources from degradation due to harmful non-native weeds by providing reliable and organized information on their distribution and ecology.
For additional information on invasive plant and animal species, including species lists, data, activities, laws, and groups working on invasive species in the United States, visit the NBII Invasive Species Node. This node also provides access to state-specific information for Arizona, Colorado, Nevada, New Mexico, and Utah.
Additional Resources
Large Zebra Mussel Cluster [Photo: US Fish and Wildlife Service]
Description:Leafy spurge is an erect, branching, perennial herb 2 to 3.5 feet tall, with smooth stems and showy yellow flower bracts. Stems frequently occur in clusters from a vertical root that can extend many feet underground. The leaves are small, oval to lance-shaped, somewhat frosted and slightly wavy along the margin.
Leafy spurge is an ecological threat. It displaces native vegetation in prairie habitats and fields through shading and by usurping available water and nutrients and through plant toxins that prevent the growth of other plants underneath it. Leafy spurge is an aggressive invader and, once present, can completely overtake large areas of open land.
Life History:Leafy spurge reproduces readily by seeds that have a high germination rate and may remain viable in the soil for at least seven years, enhancing its chances of recovery over time. Its seed capsules open explosively, dispersing seed up to 15 feet from the parent plant and may be carried further by water and wildlife. Leafy spurge also spreads vegetatively at a rate of several feet per year. The root system is complex, can reach 15 or more feet into the ground, and may have numerous buds.
Habitat:In the United States, leafy spurge tolerates moist to dry soil conditions but is most aggressive under dry conditions where competition from native plants is reduced. It is capable of invading disturbed sites, including prairies, savannas, pastures, abandoned fields and roadside areas.
Distribution:
Leafy spurge occurs across much of the northern U.S., with the most extensive infestations reported for Montana, North Dakota, Nebraska, South Dakota, and Wyoming. It has been identified as a serious pest on a number of national parks and on preserves of The Nature Conservancy in eleven northern states.
![Large Zebra Mussel Cluster [Photo: US Fish and Wildlife Service]](https://cybercemetery.unt.edu/archive/nbii/20120112032622im_/http://www.nbii.gov/portal/server.pt/gateway/PTARGS_0_2_25354_1843_6982_43/http%3B/cbi-lap7.cbi.cr.usgs.gov%3B7097/publishedcontent/publish/geographic/southwest/swin_invasives_additional_resources_highlights__narrow_/swin_additional_resources_for_invasives_highlight__narrow__1.jpg)
