The following are high priority species throughout the watershed. Unless otherwise noted, all information was gathered from the Alaska Exotic Plant Information Clearinghouse and the pocket field guide Selected Invasive Plants of Alaska (2004), published by the U.S. Forest Service. Pocket guides are available at the CRWP office.
Elodea (Elodea sp.) can form dense mats, displace native plants, decrease productivity in plankton and lower biodiversity. Elodea has been identified as a state-wide priority and has been found in Eyak Lake in Cordova and in several lakes and sloughs on the Copper River Delta. Eyak Lake is used frequently for floatplane docking and take-off and poses a significant threat as a point of distribution for Elodea to more remote lakes and aquatic systems on the Copper River Delta, in the Copper Basin, and in Prince William Sound. The Copper River Watershed Project is working closely with the U.S. Forest Service and State of Alaska to develop a management plan for Elodea in Cordova and on the Copper River Delta. For more information, please see our page on Elodea.
Identification: Elodea has submerged leaves and fibrous roots. Stems are leafless near the base an 20-100 cm long. Leaves are arranged in whorls of 3 around the steam, but towards the bottom are occasionally opposite. (photo credit: Robert Vid, Bugwood.org)
Dense mats of Elodea washed up on the shores of Eyak Lake.
White sweetclover (Melilotus alba) forms dense stands, overshadows lower growing plants, and changes soil chemistry to make it inhospitable to native plants. It contains coumarin that is toxic to animals, and has the potential to alter sedimentation rates of river systems due to its ability to colonize on gravel bars, especially in glacial systems.
Identification: Plants can grow to 6 feet tall. They have a sweet scent and many-branched stems. Leaves are toothed, oblong to lance-shaped and have 3 leaflets. Flowers are small and taper to a spike-shaped cluster at the end of branches. (photo credit: Rob Routledge, Sault College, Bugwood.org)
Bird vetch (Vicia cracca) reproduces by seed and vegetatively by underground rhizomes, making it a very aggressive weed. It climbs fencing, trees, bushes and other vegetation, outcompeting its host for sunlight, space and moisture. Spreads along roads, trails and other disturbed areas.
Identification: Multiple, branching vine-like stems that have small tendrils and alternate, compound leaves with 8-10 leaflets. Purple flowers are arranged on a one-sided spike and mature into inch-long, lance-shaped pods that contain seeds. (Photo Credit: Bonnie Million, National Park Service, Bugwood.org)
Narrowleaf hawksbeard (Crepis tectorum) is often found on disturbed soil, waste places, riverbars or roadsides. Competes with seedlings and forage. Spreads into riparian areas.
Identification: Lance-shaped leaves grow at the base of the plant and have toothed edges. Leaves on the stem clasp the stem. Dandelion-like flowers are smooth and lack hairs.
(photo credit: Caleb Siemmons, University of Maine, Bugwood.org)
Oxeye daisy (Leucanthemum vulgare) is common on roadsides and other disturbed areas and is frequently a component of wildfower seed mixes. It can form dense colonies, is unpalatable to grazing animals and insects, and hosts several plant viruses. Large infestations can cause soil erosion.
Identification: White flowers with yellow centers. Leaves hairless to sparsely hairy, alternate along the stem and get smaller towards the top. Upper leaves toothed. (photo credit: Dave Powell, U.S. Forest Service, Bugwood.org)
Reed canarygrass (Phalaris arundinacea) forms dense, persistent monocultures in wetlands and in disturbed areas. Dense stands can promote silt deposition and constrict waterways, and may even alter soil hydrology.
Identification: Reed canarygrass has hollow stems, 6-8 feet tall, with a bluish-green waxy coating. Leaves clasp stem. Seedheads start compact and then open at maturity. (Photo credit Jamie Nielsen, University of Alaska Fairbanks, Cooperative Extension Service, Bugwood.org)
Bohemian knotweed (Fallopia x bohemica) is a hybrid between Japanese knotweed and giant knotweed. It spreads mostly by stem and root fragments and forms monocultures and reduces plant diversity by replacing and eliminating native vegetation. It can clog waterways and lowers the quality of habitat for wildlife and fish, reducing food supplies for juvenile salmon in the spring.
Identification: Bohemian knotweed has characteristics of both giant and Japanese knotweed because it is a hybrid of these species. (Middle specimen in image.) It usually grows 6.5-10 feet tall and has a hollow, cane-like stem. Leaves can be either spade or heart-shaped and have short, triangular-shaped hairs on the bottom. Flowers are small, cream to greenish white and grow in plume-like, branched clusters from leaf axils near the end of stems. Fruit is 3-sided, black and shiny. (photo credit Barbara Tokarska-Guzik, University of Silesia, Bugwood.org)
Orange hawkweed (Hieracium aurantiacum) spreads by seed, rhizomes and horizontal runners and establishes dense monocultures, lowering biodiversity and outcompeting native species. Gardeners often introduce it to an area because they are attracted to its colorful flower. Spreads effectively along roads, riparian areas and beaches.
Identification: Colorful orange-red flowers. Leaves clustered in a small basal rosette and are covered with white hairs. Stems have shorter dark colored hairs. (photo credit Michael Shephard, USDA Forest Service, Bugwood.org)