Status of Invasive Plants in Maryland

Invasive Plants by Category

• Aquatic - 9 species, 38 records
• Conifer Trees - 3 species, 9 records
• Forbs/Herbs - 197 species, 2041 records
• Grass or Grasslike - 68 species, 1008 records
• Hardwood Trees - 48 species, 526 records
• Shrub or Subshrub - 57 species, 776 records
• Vines - 28 species, 666 records

Top Ten Abundant Invasive Plants (by number of reports)

1. tree-of-heaven - 278 reports
2. wavyleaf basketgrass - 262 reports
3. Japanese honeysuckle - 238 reports
4. multiflora rose - 226 reports
5. Nepalese browntop - 184 reports
6. garlic mustard - 137 reports
7. Japanese barberry - 107 reports
8. exotic bush honeysuckles - 98 reports
9. Japanese hop - 98 reports
10. wine raspberry - 83 reports

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

1. mile-a-minute weed - 22/24 (92%)
2. Canada bluegrass - 22/24 (92%)
3. Asiatic dayflower - 21/24 (88%)
4. buckhorn plantain - 21/24 (88%)
5. Japanese honeysuckle - 20/24 (83%)
6. bald brome - 20/24 (83%)
7. red sorrel - 20/24 (83%)
8. curly dock - 20/24 (83%)
9. Nepalese browntop - 19/24 (79%)
10. bermudagrass - 19/24 (79%)

Counties with the most invasive species reported

1. Prince George's County - 348 species
2. Montgomery County - 292 species
3. Baltimore County - 248 species
4. Calvert County - 215 species
5. Frederick County - 204 species
6. Cecil County - 201 species
7. Howard County - 199 species
8. Worcester County - 180 species
9. Anne Arundel County - 175 species
10. Washington County - 145 species

Counties with the least invasive species reported

1. Somerset County - 42 species
2. Baltimore city - 43 species
3. Queen Anne's County - 55 species
4. Dorchester County - 74 species
5. St. Mary's County - 75 species
6. Wicomico County - 77 species
7. Charles County - 87 species
8. Carroll County - 93 species
9. Harford County - 100 species
10. Allegany County - 108 species