Like many young English blades, Rolfe smoked—or, as the phrase went in those days, "drank"—tobacco, a fad since the Spanish had first carried back samples of Nicotiana tabacum from the Caribbean. Indians in Virginia also drank tobacco, but it was a different species, Nicotiana rustica. Virginia leaf was awful stuff, wrote colonist William Strachey: "poor and weak and of a biting taste." After arriving in Jamestown in 1610, Rolfe talked a shipmaster into bringing him N. tabacum seeds from Trinidad and Venezuela. Six years later Rolfe returned to England with his wife, Pocahontas, and the first major shipment of his tobacco. "Pleasant, sweet, and strong," as Rolfe's friend Ralph Hamor described it, Jamestown's tobacco was a hit. By 1620 the colony exported up to 50,000 pounds (23,000 kilograms) of it—and at least six times more a decade later. Ships bellied up to Jamestown and loaded up with barrels of tobacco leaves. To balance the weight, sailors dumped out ballast, mostly stones and soil. That dirt almost certainly contained English earthworms.
And little worms can trigger big changes. The hardwood forests of New England and the upper Midwest, for instance, have no native earthworms—they were apparently wiped out in the last Ice Age. In such worm-free woodlands, leaf litter piles up in drifts on the forest floor. But when earthworms are introduced, they can do away with the litter in a few months. The problem is that northern trees and shrubs beneath the forest canopy depend on that litter for food. Without it, water leaches away nutrients formerly stored in the litter. The forest becomes more open and dry, losing much of its understory, including tree seedlings.
Whether the night crawler and the red marsh worm actually first arrived on Rolfe's tobacco ships is not known. What is clear is that much of the northern forests in America were worm free until the Europeans arrived there, inadvertently importing earthworms on the root-balls of their plants or in the ballast of ships. The effects of this earthworm invasion have been slow to show themselves because the creatures don't spread rapidly on their own. "If they're born in your backyard, they'll stay inside the fence their whole lives," says John Reynolds, editor of Megadrilogica, the premier earthworm journal. But over time, the effect on the ecosystem can be dramatic.
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