Plants on the prowl

Invasive plant species can pose a dangerous threat to native plant communities. When such a species is detected, it’s up to humans to take the initiative, such as when natural resources professionals recently removed crown vetch and honeysuckle from the Rock Springs Conservation Area in Chicago. Crown vetch is used in many places for erosion control and soil rehabilitation, but its sturdy, aggressive nature allows it to easily take over garden areas and crowd out other species. Honeysuckle, on the other hand, simply had the misfortune to be a non-native plant in the area without the proper conditions to keep it under control.Some invasive plant species are quite well known. For instance, the kudzu vine has become known as the “mile-a-minute vine” or even “the vine that ate the South” in the United States. Among the plant’s special features are: the ability for its seeds to germinate for several years, causing it to reappear at sites where it was thought eradicated; the lack of natural predators; and its famed growing speed (currently about 150,000 acres annually in the southern U.S.).Yellow starthistle became an invasive species when it was introduced to California in the 19th century. Today, it covers over 15,000,000 acres of the state. The plant has the ability to survive periods of low moisture by producing smaller plants with less seeds. Like crown vetch, yellow starthistle is poisonous to horses. In particular, the plant produces the condition known as chewing disease.

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