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Status of Invasive Plants in Washington

Total number of exotic species reported: 605

Total number of records in EDDMapS: 23568


Invasive Plants by Category

  • Aquatic - 16 species, 1706 records
  • Conifer Trees - 2 species, 2 records
  • Forbs/Herbs - 371 species, 13002 records
  • Grass or Grasslike - 95 species, 3428 records
  • Hardwood Trees - 43 species, 622 records
  • Shrub or Subshrub - 48 species, 1231 records
  • Vines - 30 species, 1054 records

Top Ten Abundant Invasive Plants (by number of reports)

  1. common yarrow - 1626 reports
  2. cheatgrass - 553 reports
  3. Himalayan blackberry - 425 reports
  4. common St. Johnswort - 399 reports
  5. Eurasian water-milfoil - 380 reports
  6. yellow iris - 305 reports
  7. purple loosestrife - 258 reports
  8. Canada thistle - 255 reports
  9. foxglove - 248 reports
  10. bull thistle - 246 reports

Top Ten Widespread Invasive Plants (by number of positive counties)

  1. Canada thistle - 39/39 (100%)
  2. bull thistle - 39/39 (100%)
  3. common yarrow - 39/39 (100%)
  4. field bindweed - 39/39 (100%)
  5. common St. Johnswort - 39/39 (100%)
  6. oxeye daisy - 38/39 (97%)
  7. reed canarygrass - 38/39 (97%)
  8. spotted knapweed - 37/39 (95%)
  9. Japanese knotweed - 37/39 (95%)
  10. diffuse knapweed - 37/39 (95%)

Counties with the most invasive species reported

  1. King County - 465 species
  2. Klickitat County - 375 species
  3. Whitman County - 347 species
  4. San Juan County - 333 species
  5. Okanogan County - 300 species
  6. Walla Walla County - 282 species
  7. Pierce County - 281 species
  8. Whatcom County - 271 species
  9. Spokane County - 269 species
  10. Pend Oreille County - 261 species

Counties with the least invasive species reported

  1. Douglas County - 98 species
  2. Franklin County - 114 species
  3. Garfield County - 128 species
  4. Lincoln County - 135 species
  5. Mason County - 145 species
  6. Adams County - 149 species
  7. Grant County - 162 species
  8. Jefferson County - 168 species
  9. Wahkiakum County - 169 species
  10. Grays Harbor County - 170 species

Report created on July 25, 2014 at 12:01 PM by the UGA Center for Invasive Species and Ecosystem Health using EDDMapS Technology and Data.