Status of Invasive Plants in Maryland

Invasive Plants by Category

• Aquatic - 9 species, 112 records
• Conifer Trees - 3 species, 9 records
• Forbs/Herbs - 205 species, 2243 records
• Grass or Grasslike - 74 species, 1129 records
• Hardwood Trees - 53 species, 601 records
• Shrub or Subshrub - 62 species, 995 records
• Vines - 29 species, 958 records

Top Ten Abundant Invasive Plants (by number of reports)

1. tree-of-heaven - 317 reports
2. multiflora rose - 284 reports
3. wavyleaf basketgrass - 284 reports
4. Japanese honeysuckle - 275 reports
5. mile-a-minute weed - 234 reports
6. Japanese stiltgrass - 219 reports
7. garlic mustard - 196 reports
8. Japanese barberry - 183 reports
9. Japanese hop - 124 reports
10. wine raspberry - 115 reports

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

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

Counties with the most invasive species reported

1. Prince George's County - 355 species
2. Montgomery County - 304 species
3. Baltimore County - 254 species
4. Calvert County - 215 species
5. Frederick County - 207 species
6. Howard County - 204 species
7. Cecil County - 204 species
8. Anne Arundel County - 193 species
9. Worcester County - 180 species
10. Washington County - 150 species

Counties with the least invasive species reported

1. Somerset County - 43 species
2. Baltimore city - 44 species
3. Queen Anne's County - 57 species
4. Dorchester County - 75 species
5. Wicomico County - 78 species
6. St. Mary's County - 80 species
7. Charles County - 92 species
8. Carroll County - 98 species
9. Harford County - 104 species
10. Kent County - 113 species