Describing a weed as invasive means that the weed is a non-native (or alien) plant species introduced to an ecosystem where it is not originally from, and it tends to spread rapidly and uncontrollably. These invasive weeds establish, persist, and spread widely in natural ecosystems outside their native range. Because they lack natural enemies in the new environment, they can outcompete and crowd out native plants, often causing environmental harm by disrupting local ecosystems. Invasive weeds can also cause economic damage and sometimes pose health risks. The "invasive" label usually implies the weed is foreign to the region and is causing harm through its aggressive spread and impact on native flora and habitats.