Finding Native vs. Introduced Plant Ratios for Your Region

Finding Native vs. Introduced Plant Ratios for Your Region

There's no universal ratio of native to introduced plants—the answer depends entirely on your specific ecoregion and how well it's been studied.

How to Research Your Area

1. Contact your state's native plant society or department of agriculture.
2. Check university extension publications for flora surveys.
3. Use the USDA PLANTS Database (plants.usda.gov) for county-level distribution maps.
4. Consult local conservation districts—they often have invasive species lists and native plant guides.

Example: Oregon

The Oregon Department of Agriculture maintains a plant conservation page with lists of endangered natives and invasive introduced species: ODA Plant Conservation.

Start with your state's natural heritage program for the most accurate, localized data.