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The Weeds that Settlers Spread

Common ragweed (Ambrosia artemisiifolia) is spreading throughout Europe, and allergy sufferers farther south on the continent now have yet another reason to dread pollen season.

A single plant can produce up to one billion pollen grains in one season. But it is also a weed that can be a nuisance for farmers.

The plant is native to North America, and a big part of why it has become so widespread is probably due to European activity there over the last five centuries.

Before Europeans established themselves on North America in the 1500s, ragweed’s range was limited. Today, the plant has spread to every continent except Antarctica.


“Ragweed probably spread in North America via settlers who picked it up on their wagons when they cleared farmland and cut down forests,” says Michael D. Martin.

Read more of the Sciencedaily news story here.