“Throughout the long history of our species, humans have moved other organisms. Sometimes on purpose, sometimes by accident. It's part of what we do. Once in a while, a species we've moved has found itself in virgin territory and has spread rapidly, changing the landscape for ever. Plants that seem to suddenly "take over" are labeled "invasive," meaning that they have characteristics in their abilities to disperse and spread that let them do damage to otherwise intact ecological systems. This is a serious problem, both in conservation terms and in economic terms.” Canadian Botanical Conservation Network