Noxious WeedsRedding Field Office
Noxious Weeds

 This plant guide identifies eighteen noxious weeds that are known to occur on public lands administered by the Bureau of Land Management's Redding Field Office in northern California.  To view a photograph and more information on an individual plant, click on the plant's common name below.

Photo of Tree-of-Heaven
Ailanthus altissima

Yellow Starthistle
Photo of Yellow Starthistle
Centaurea solstitialis

Scotch Broom
Photo of Scotch Broom
Cytisus scoparius

 Klamathweed or
St. Johnswort
Photo of Klamathweed
Hypericum perforatum

Dalmatian Toadflax
Photo of Dalmatian Toadflax
Linaria dalmatica

Himalayan Blackberry
Photo of Himalayan Blackberry
Rubus discolor

Medusahead Grass
Photo of Medusahead Grass

Marlahan Mustard
Marlahan Mustard
Isatis tinctoria

Giant Reed
Giant Reed
Arundo donax

Sesbania punicea

Perennial Pepperweed
Perennial Pepperweed
Lepidium latifolium

Spotted Knapweed
Spotted Knapweed
Centaurea maculosa

Diffuse Knapweed
Diffuse Knapweed
Centaurea diffusa

Squarerose Knapweed
Squarerose Knapweed
Centaurea squarrosa

Tribulus terrestris

French Broom
French Broom photo courtesy of NPS
Genista monspessulana

Salt Cedar
Salt Cedar
Tamarix ramosissima
Spanish Broom
Spanish Broom photo courtesy of NPS
Spartium junceum

Noxious weeds are non-native plants introduced to North America from Europe and Asia. These plants have spread at an alarming rate because, unlike native species, there are no native insects, fungi, or diseases to control their growth and spread in this country. What began as a handful of plants introduced in the 19th century, now number in the hundreds of millions. Noxious weeds destroy wildlife habitat and forage, threaten endangered species and native plants, increase erosion and groundwater loss, and prevent recreational activities.

Estimates indicate that noxious weeds are spreading at rate of 4,600 acres per day on federal lands alone in the western United States.  They have invaded approximately 17 million acres of public rangelands in the West -- more than quadrupling their range from 1985 to 1995. In northern California, yellow starthistle expanded its range from 1 million acres in 1981 to 10 million acres in 1997.

The Bureau of Land Management is just one of many government agencies mounting an effort to control and prevent noxious weeds, as well as educate the public about how destructive these plants can be.