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Status of Invasive Plants in Washington

Total number of exotic species reported: 601

Total number of records in EDDMapS: 24016


Invasive Plants by Category

  • Aquatic - 16 species, 1713 records
  • Conifer Trees - 2 species, 2 records
  • Forbs/Herbs - 368 species, 12752 records
  • Grass or Grasslike - 95 species, 3430 records
  • Hardwood Trees - 43 species, 627 records
  • Shrub or Subshrub - 48 species, 1236 records
  • Vines - 29 species, 1066 records

Top Ten Abundant Invasive Plants (by number of reports)

  1. common yarrow - 1642 reports
  2. cheatgrass - 553 reports
  3. Himalayan blackberry - 429 reports
  4. common St. Johnswort - 399 reports
  5. Eurasian water-milfoil - 380 reports
  6. yellow iris - 307 reports
  7. purple loosestrife - 261 reports
  8. Canada thistle - 255 reports
  9. bull thistle - 249 reports
  10. foxglove - 248 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. diffuse knapweed - 37/39 (95%)
  10. purple loosestrife - 36/39 (92%)

Counties with the most invasive species reported

  1. King County - 478 species
  2. Klickitat County - 387 species
  3. Whitman County - 354 species
  4. San Juan County - 338 species
  5. Okanogan County - 309 species
  6. Pierce County - 292 species
  7. Walla Walla County - 291 species
  8. Whatcom County - 282 species
  9. Spokane County - 279 species
  10. Pend Oreille County - 271 species

Counties with the least invasive species reported

  1. Douglas County - 106 species
  2. Franklin County - 116 species
  3. Garfield County - 138 species
  4. Lincoln County - 140 species
  5. Mason County - 153 species
  6. Adams County - 154 species
  7. Grant County - 164 species
  8. Wahkiakum County - 175 species
  9. Jefferson County - 177 species
  10. Grays Harbor County - 178 species

Report created on July 29, 2015 at 05:45 AM by the UGA Center for Invasive Species and Ecosystem Health using EDDMapS Technology and Data.