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December 09, 2016
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Plants behaving badly; Love that ‘ornamental’ plant? Not so fast, please

Garlic mustard is a biennial herb, one of the first to come up in the spring. Growing up to four feet tall, it’s a common invader of roadsides and forests.

Where did the invaders come from and how did they get here? They came to North America from all over the world. Some were introduced inadvertently, arriving as seed and spore stowaways. Others were imported deliberately by immigrants seeking to recreate the farms, gardens, products and vistas of their homelands. If all non-native plants were invasive, life as we know it would have ceased before now. Most non-native plants are not invasive and adapt well to their new environments, causing little or no damage to ecosystems. Some co-exist harmoniously for generations, becoming invasive only after climate, growing season or land development conditions alter significantly. Although biologists and botanists admit that it’s difficult to predict with absolute certainty which non-native plants will become invasive, they have identified hallmarks common to most invasive plant species. These include: climatic pre-adaptation; early and frequent production of copious amounts of seed; effective seed dispersal mechanisms; lack of highly specific pollinator requirements; and effective means of vegetative spread. In other words, these plants have developed versatile, highly efficient methods of rapid growth and propagation.


Why has dramatic proliferation of invasive plants gone undetected for so long? Biologist Jamie Myers of the National Park Service in Milanville, PA says simply, “For the most part, the public doesn’t recognize invasive plants when it sees them.” Few Americans today, even those who have long resided in rural areas, are as familiar with local flora as were their agrarian ancestors. And that, Myers says, is what must change before the tide turns in the battle to contain invasive plants. To that end, federal agencies are partnering with private nonprofit conservation organizations to educate Americans about invasive plants, the conditions that foster their proliferation, and the means to manage and eradicate them. The NPS plans to conduct workshops this summer aimed at teaching the public how to identify, manage and eradicate invasive land and aquatic plant species.