Definition: Invasive plants are species that show a tendency to spread out of control. Although not synonymous with "exotic plants" ("alien plants"), invasive plants often are plants that have been introduced from other regions and spread like wildfire in their new habitats. It is thought that the tendency of invasive plants to spread so much is due in part to the fact that the insects and diseases that plague them in their native lands are often absent in their new homes, where the invasive plants thus enjoy "free rein."
Helping invasive plants spread in some cases are extensive underground networks of roots called, "rhizomes." The rhizomes are so widespread that attempting to dig them up in order to eradicate the invasive plants is usually fruitless.
Invasive plants compete so successfully against other plants that they can crowd out their competitors, thus producing a monoculture that discourages the growth of other plant varieties. Exotic invasive plants often crowd out indigenous plants in this manner. A classic case of exotic invasive plants forming such a monoculture can be seen in entrenched stands of Japanese knotweed, which have notoriously vigorous rhizomes.
Landscapers need to act aggressively to eradicate invasive plants that invade the lawn or garden ("weeds").
Also Known As: invasive species (there are invasive species in both the animal and vegetable kingdoms)
Examples: Some species formerly installed by highway crews to control soil erosion on the edges of roads are now considered "invasive plants."
