Book excerpt: Since the publication of the first edition of this book in 2003, the status of many important invasive plants around the world has changed dramatically. Species have extended their ranges, new literature has been accumulated, and control methods have been improved. Research on some plant invaders has also focused on the species' ecology and impacts, confirming that invasive plants continue to pose serious threats to species and ecosystems. Given their range expansions and introduction via international trade, these problems will only become more serious in the future. Including colour images of each species, this up-to-date reference guide on the most important plant invaders is an invaluable tool for both researchers and policy makers.