This plant guide identifies 25 noxious weeds that are known to occur on public land administered by the Bureau of Land Management's Eagle Lake Field Office, located in northeastern California. To view a photograph and more information on an individual plant, click on the plant's common name below. Musk Thistle Carduus nutans Plumeless Thistle Carduus acanthoides Scotch Thistle Onopordum acanthium Wavyleaf Thistle Cirsium undulatum Yellowspine Thistle Cirsium ochrocentrum Yellow Starthistle Centaurea solstitialis Diffuse Knapweed Centaurea diffusa Russian Knapweed Acroptilon repens Spotted Knapweed Centaurea maculosa Squarrose Knapweed Centaurea sqarrosa Common Crupina or Bearded Creeper Crupina vulgaris . Mustard Isatis tinctoria .
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. In northern California, yellow starthistle expanded its range from 1 million acres in 1981 to 10 million acres in 1997.