Plants that spread where they're unwanted are called invasive. Many of these are imported (also called nonnative or exotic) species that become wildly successful when given a chance to grow in the absence of the natural predators or limiting environmental conditions that were present in their homeland. This is the case with bindweed. Other nonnative species become invasive by producing huge crops of berries (Oriental bittersweet, autumn olive, and privet, to name a few), or by growing with nearly supernatural energy, as do kudzu and Japanese honeysuckle. Sometimes even native plants can become invasive when given a boost by the comforts of cultivation. This often happens with brambles, wild vines such as trumpet vine, and even some ferns. Whenever a plant seems to like your yard a little too well, begin to control it early, before its high spirits become a headache. Better yet, check a plant's invasive reputation before adding it to your landscape. One of the best websites for this information is www.invasive.org, where you can search for invasive plants by their name or the state where they are a problem. Some plants that are well-behaved in certain regions may be problematic in others.