Beautiful Invasion: Invasive Plants

They're beautiful. They're exotic. They're disease resistant. They grow fast and spread rapidly. What's not to love about these foreign transplants? Well, first of all, given the right conditions, they will reseed like crazy and replicate like creatures from outer space. They will spread like wildfire and cover every native plant in their path. They can climb a tree, overwhelm it, and, in many cases, kill it down to its roots.

If you live in Zone 6 and below, these are the invasive beauties to avoid:

• Kudzu (Pueraria lobata): Native to Japan, this vine was introduced to America, for ornamental purposes and erosion control, back in 1876. What were they thinking? Today, "The Vine That Ate The South" smothers banks, arbors, telephone poles, trees, houses and fields. It is actually quite lovely, with bright green leaves and fragrant red purple flowers, in clusters 8-12 inches long. However, growing at a rate of a foot a day, this vine should be avoided, unless you are hiding from the law. Projects are underway to eradicate this species, with the hope of importing, from Japan, its natural insect predators. Let's hope this quest doesn't create even more problems.
  
• Purple Loosestrife (Lythrum salicara): This plant is both hated and loved. Radiantly beautiful, this plant is killing our wetlands. It was introduced from Europe in the mid-1800s. Escaping from the garden, it has made its home in a favorite habitat, the fast vanishing marshes and estuaries of the U.S. The tall purple flowered plant, with its magnificent spires of blooms, spreads at an alarming rate, crowding out our native wetland species and destroying huge areas of natural wildlife habitat. It both reseeds and spreads by underground shoots, faster than any native species. You can no longer purchase these seeds or plants in the U.S. from reputable nurseries.
  
• Creeping Jenny (Lysimachia nummularia 'Aurea'): A single plant of this radiant groundcover will eclipse a slope in a season. It simply grows and spreads in shady moist soil, choking out less vigorous plantings, and growing up and over larger species. The roots are extremely invasive, robbing nutrients from other plants, and they are devilishly hard to dig out. If a single stem is left in the ground, come spring it will begin the invasion again. I have found that the only way to get rid of this invasive groundcover was to smother it under layers of newspaper and mulch. Although this plant can still be found at nurseries, I would avoid it and choose a less invasive groundcover.
  
• Water Hyacinth (Eichhornia crassipes): Imported from Brazil in 1884, this gorgeous floating plant has taken over our waterways, choking ponds, canals, and swamps. Spread by current and wind, this 2 foot wide invasive, with its breathtaking flowers of yellow and blue, has become a million dollar problem from Florida to California. Like all foreign invasives it has no natural enemies in the U.S., so it continues to invade our estuaries and wetlands, and destroy native species. If introduced to garden ponds, it will quickly destroy beneficial vegetation and steal the oxygen from the fish. Avoid this plant at all cost.
  
• Mimosa or Silk Tree (Albizia julibrissin): Graceful and beautiful, the Mimosa is one of the loveliest large trees to over-populate the south. It's fragrant "cotton candy" blooms are a favorite of hummingbirds. A native of Asia, this tree flourishes as far North as zone 6, and once you have one tree, you will have a hundred. According to a renowned British seed company, germinating Mimosa seeds is a little tricky, requiring understanding and experience. I disagree. I have found that to germinate a thousand seeds, all you need is a patch of dirt or a crack in the sidewalk. Once invaded, you will be fighting seedlings for years, long after this short-lived tree is cut down. Do not plant this tree unless you have acres of land. Avoid planting near anything. It will germinate so fast and reseed by the hundreds, year after year. It is like a lovely disease that you will never be able to control. Avoid this tree like the plague.
  
• Japanese Honeysuckle (Lonicera japonica): This fragrant vine with its unremarkable flowers, can be found taking over everything across the south and midwest. Often grown as a groundcover on banks, or for erosion control, this invasive transplant has become a noxious weed. It smothers everything less vigorous, even your roses and ornamentals of any size. While its scent is heavenly, I would avoid this Japanese native entirely.

Many plants and trees have been introduced to the U.S., and they have become a welcome part of our gardening culture. They are not all bad plants, although there are some native purists who would argue that no non-native should be allowed to germinate in U.S. soil. However, many non-natives have been used to strengthen native plants overcome by disease, such as the beautiful native dogwood or the blighted American chestnut. It is the wise gardener who studies each new introduction carefully, understanding that what is beautiful is not necessarily beneficial. In this way one can win the fight before the battle begins.