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Weeds

Yellow StarthistleInvasive plants are one of the biggest threats to native plants, wildlife and habitats in the United States. The Hanford Reach National Monument is plagued by numerous species. One species—cheatgrass—is so pervasive that it isn't even listed as a weed anymore!

Prior to alteration of the shrub-steppe of eastern Washington in the 1800's, big sagebrush/bluebunch wheatgrass was the dominant vegetation type over much of the Columbia Basin. Although the Monument area has documented large, relatively undisturbed shrub-steppe plant communities, many previously disturbed areas have altered vegetative communities. One of the primary significant changes to the vegetative communities is the invasion of non-native plant species. Once introduced, these species can proliferate because of the lack of natural predators, or because they can out-compete native plant species in disturbed habitats. Moreover, some species are aggressive enough to be successful in invading even intact native plant communities.

Disturbed areas of the Monument units usually are dominated by cheatgrass and other exotic species cover with or without big sagebrush. Cheatgrass is a particularly competitive plant that favors disturbed areas and has several characteristics that enhance its ability to establish and persist, including the ability to germinate in the spring or fall, high seed production, greater germinability than native grasses and tolerance to grazing. Within several areas the native vegetation has likely been permanently replaced by cheatgrass and other non-native plants, particularly in areas where historic disturbances were the most intense (especially on historically farmed and grazed locations). Vegetation within these areas have highly variable shrub cover, high cover of cheatgrass, frequently a significant cover of Sandberg's bluegrass, and usually a low cover of microbiotic crust. It is unlikely that native bunchgrasses will become established without extensive restoration. Additionally, noxious weeds and other aggressive non-native plants tend to invade and become established more readily within previously disturbed habitats. The invasion of non-native plants represents a threat to the integrity of the Monument and the preservation of its unique biodiversity.

In any effort to assist FWS staff in identifying weeds, the Monument has put together its own 'weed book.' Familiarizing yourself with these weeds, and taking steps to prevent their spread, will help us protect this landscape into tomorrow.

Invasive Species (Weed) Inventory & Management Plan (PDF - 1.36MB)

Complete Hanford Reach National Monument Weed Book (PDF - 4.5MB)

Individual weed pages: 

  1. About Weeds—36 KB PDF
  2. Terminology and Disposal—34 KB PDF
  3. Yellow Starthistle (Centaurea solistitialis L.)—362KB PDF
  4. Rush Skeletonweed (Chondrilla juncea L.)—550KB PDF
  5. Salt Cedar (Tamarix ramosissima Ledeb.)—456KB PDF
  6. Purple Loosestrife (Lythrum salicaria L.)—298KB PDF
  7. Puncturevine, Bullhorns, Goathead, Sandbur (Tribulus terrestris L.)—640KB PDF
  8. Russian Knapweed (Centaurea repens L.)—442KB PDF
  9. Perennial Pepperweed, Hoary Cress and related Whitetops (Lepidim latifolium L., Cardaria draba (L.) Desv., C. pubescens (C.A. Meg Jarmolenko), and C. chalapensis L.)—374KB PDF
  10. Diffuse Knapweed, Tumble Knapweed (Centaurea diffusa Lam.)—561KB PDF
  11. Spotted Knapweed (Centaurea biebersteinii DC. = Centaurea maculosa Lam.)—648KB PDF
  12. Hairy Willow-herb (Epilobium hirsutum)—202KB PDF
  13. Dalmatian Toadflax (Linaria dalmatica L.)—500KB PDF
  14. Camelthorn (Alhagi Pseudalhagi Bieb.)—517KB PDF
  15. Canada Thistle (Cirsium arvense L.)—252KB PDF
  16. Scotch Thistle (Onopordum acanthium L.)—225KB PDF
Page Photo Credits — Yellow Starthistle - Martin Jambon
Last Updated: May 03, 2013
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