Invasion of the Habitat Snatchers

As you wander the Middle brook trail, you may not notice the invasion occurring all around you. Yet a silent fight to the death is being waged. The winners are plants with names like purple loosestrife, Tartarian honeysuckle, Japanese barberry, and Russian olive. Spot the pattern in their names? These plants, often brought to us from overseas as garden ornamentals, have spread well beyond their intended homes, battling with native species for nutrients, water, and light.

Native plant pests, such as insects and grazing herbivores, often avoid consuming these alien plants as part of their diet, because plant and predator have evolved over thousands of years in separate places. Homeowners should learn more about alien invaders to avoid unwittingly contributing to their devastating spread.


These giant reeds, or phragmites australis, growing in the sewer easement on the east side of the trail? Phragmites is often found in wet disturbed areas and is nearly impossible to eradicate. See the multiflora rose bushes on the west side? The Soil Conservation Service imported this species decades ago to be used by farmers as a living fence. They did not expect it to take over large areas from native plant species. Their tests did not take into account that the seeds germinate easily after passing through a bird’s digestive tract.

Purple loosestrife found its’ way to America in the early nineteenth century, possibly in the ballast water of ships or in bales of wool. It likes sunny wetlands where the soil has been disturbed. It spreads aggressively here because its’ enemies were left behind in Eurasia. It grows about two feet taller here than in its’ native land and rather than remaining small clumps it can completely overrun an area. It shoulders aside native wetland plants but is not as useful to native fauna as what it crowds out.

Many methods have been tried to control it but few have worked. In 1992 the Biological Control of Non-Indigenous Plant Species Program of Cornell University got permission to import Galerucella beetles to balance the scales.

At the right time of the year the purple loosestrife, another non-native invasive plant, can be seen blooming in the detention basin late in the summer.