Native Plants That Are Also Introduced: Yarrow, Elderberry and Others

One name, two origins

For most species USDA gives a single status for the lower 48: native or introduced. For 70 plants on these county lists it gives both. Usually the species occurs naturally in North America and has also arrived from Europe or Asia, and the two populations now grow side by side - sometimes as recognisably different varieties, often not.

The ones you are most likely to meet

• Common yarrow (Achillea millefolium) - recorded in 1,996 counties
• Black elderberry (Sambucus nigra) - recorded in 1,959 counties
• Annual ragweed (Ambrosia artemisiifolia) - recorded in 1,789 counties
• Common dandelion (Taraxacum officinale) - recorded in 1,649 counties
• Kentucky bluegrass (Poa pratensis) - recorded in 1,637 counties
• Lambsquarters (Chenopodium album) - recorded in 1,599 counties

These stay on county lists, since USDA does record them as native, but the starter lists rank them lower, because what a nursery sells under the name may be the introduced form.

What to ask a nursery

If you are planting for wildlife or restoration, ask where the seed or stock came from. "Native yarrow" grown from regional wild-collected seed is a different thing from a European garden cultivar sold under the same species name. Nurseries that specialise in natives usually list the source region; a garden centre often will not know.

The counties with the most of these plants on file are Essex County, Massachusetts (40), Middlesex County, Massachusetts (38), Philadelphia County, Pennsylvania (37). USDA rates growing conditions for the species as a whole, not for one origin; for the plants recorded almost everywhere, see the most widespread natives.