Invasive Plant

Scientists often think that invasive plants succeed in a habitat because they happen to have already evolved favourable traits-a taste for the local soil, for example, or resistance to local pests. This research shows something different. It found that once relocated, a plant is able to continue to evolve rapidly to conquer its new habitat. Two biologists from the University of Toronto and the University of British Columbia did an experiment to demonstrate that purple loosestrife living in different parts of the continent is adapted to its environment. They gathered purple loosestrife from the northern and southern regions of its range, then transplanted the northerners south, and the southerners north. The researchers, Robert Colautti and Spencer Barrett, found purple loosestrife produced fewer fruits the farther away it was from its original habitat. That indicated that the plants' differences were adapted to their environments. Northern purple loosestrife has to deal with a shorter growing season, so it blooms early in the spring to take advantage of as much time as possible. Compared to southern loosestrife grown in the north, it can produce up to 37 times as many fruits. But because it blooms later, southern loosestrife can grow bigger.