Forest & Grassland Health

Invasive Plants

Pocket guide for selected invasive plants of Alaska.

 

Click cover image to view the invasive plant pocket guide. Also see the book Invasive Plants of Alaska (2009), co-authored with key partners across the state.

A common misconception is that Alaska is largely free of invasive species. In fact, more than 340 invasive plant species have been reported in Alaska. These plants vary in their level of invasiveness, which is quantified using the invasive plant ranking system. The rankings, scaled from 0 to 100, are based on species' ecological impacts, biological attributes, distributions, and responses to control measures; higher rankings correspond to greater potential harm to natural ecosystems in Alaska. The University of Alaska Anchorage Center for Conservation Science maintains the Non-native Plant Species List for Alaska, with valuable summary information on 410 invasive plants that have or may become established, invasiveness ranking scores, and links to species' biographies. In the table below, we include 30 plants with the highest invasiveness scores. The ranking system and species' biographies were developed in collaboration with the USDA-FS and the Cooperative Extension Service.

See our Invasive Plant Publications page for more resources related to invasive plant management in Alaska, the Cooperative Extension Service Invasive Plant Partnership page, and the homepage for the UAA Center for Conservation Science.
 



Non-Native Plant Species List – Alaska Center for Conservation Science
* visit the ACCS page to access the full list
 

Common Name

Scientific Name

Species Biography

Rank

Family

Est.

Occurrence

Eurasian watermilfoil

Myriophyllum spicatum L.

bio.

90

Halagoraceae

 

Alaska Watchlist

Japanese knotweed

Fallopia japonica (Houtt.) Ronse Decr.

bio

87

Polygonaceae

1981

Alaska

giant knotweed

Fallopia sachalinensis (F. Schmidt ex Maxim.) Ronse Decr.

bio. 

87

Polygonaceae

2006

Alaska

Bohemian knotweed

Fallopia ×bohemica (J. Chrtek & Chrtkov) J.P. Bailey

bio. 

87

Polygonaceae

2004

Alaska

spotted knapweed

Centaurea stoebe L.

bio. 

86

Asteraceae

2004

Alaska

smooth cordgrass

Spartina alterniflora Loisel.

bio. 

86

Poaceae

 

Alaska Watchlist

common cordgrass

Spartina anglica C.E. Hubbard

bio. 

86

Poaceae

 

Adjacent Canada only

denseflower cordgrass

Spartina densiflora Brongn.

bio. 

86

Poaceae

 

Adjacent Canada only

saltmeadow cordgrass

Spartina patens (Aiton) Muhl.

bio. 

86

Poaceae

 

Adjacent Canada only

leafy spurge

Euphorbia esula L.

--- 

84

Euphorbiaceae

2012

Alaska

purple loosestrife

Lythrum salicaria L.

bio. 

84

Lythraceae

2006

Alaska

European wand loosestrife

Lythrum virgatum L.

bio. 

84

Lythraceae

 

Alaska Watchlist

reed canarygrass

Phalaris arundinacea L. (cultivar)

bio. 

83

Poaceae

1905

Alaska

common reed

Phragmites australis (Cav.) Trin. ex Steud.

bio. 

83

Poaceae

 

Adjacent Canada only

ornamental jewelweed

Impatiens glandulifera Royle

bio. 

82

Balsaminaceae

2004

Alaska

giant hogweed

Heracleum mantegazzianum Sommier & Levier

bio

81

Apiaceae

2010

Alaska

white sweetclover

Melilotus albus Medik.

bio.

81

Fabaceae

1913

Alaska

waterthyme

Hydrilla verticillata (L. f.) Royle

bio.

80

Hydrocharitaceae

 

Alaska Watchlist

American white waterlily

Nymphaea odorata Aiton ssp. odorata

bio. 

80

Nymphaeaceae

1997

Alaska

Himalayan knotweed

Persicaria wallichii Greuter & Burdet, Willd.

bio.

80

Polygonaceae

2006

Alaska

Canadian waterweed

Elodea canadensis Michx.

bio. 

79

Hydrocharitaceae

1982

Alaska

western waterweed

Elodea nuttallii (Planch.) H. St. John

bio. 

79

Hydrocharitaceae

1982

Alaska

orange hawkweed

Hieracium aurantiacum L.

bio. 

79

Asteraceae

1969

Alaska

meadow hawkweed

Hieracium caespitosum Dumort.

bio.

79

Asteraceae

2004

Alaska

cheatgrass

Bromus tectorum L.

bio. 

78

Poaceae

1923

Alaska

Himalayan blackberry

Rubus discolor Weihe & Nees

bio.

77

Rosaceae

2006

Alaska

Canada thistle

Cirsium arvense (L.) Scop.

bio.

76

Asteraceae

1925

Alaska

Siberian peashrub

Caragana arborescens Lam.

bio.

74

Fabaceae

1995

Alaska

European bird cherry

Prunus padus L.

bio. 

74

Rosaceae

1980

Alaska

chokecherry

Prunus virginiana L.

bio. 

74

Rosaceae

2009

Alaska

 

Links & Resources

 

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