Starting to research a piece on the newest invasive plants and animals attacking us and ran across a piece I wrote about three years ago on some of our worse invasive. Pic is the dreaded tree from heaven. I have one growing now out of a storm gutter grate. These things are incredible, they can thrive anywhere….
By Bob Quarteroni
You don’t need to scan the sky for signs of alien invaders.
Just look at your feet.
Alien plants — invasives from around the world — have transformed our environment, often outcompeting native plants in the struggle for space — and survival.
And it’s a huge problem. According to a report from Cornell University, “Invading non-indigenous species in the United States cause major environmental damages and losses adding up to more than $138 billion per year. There are approximately 50,000 foreign species and the number is increasing. About 42 percent of the species on (our) Threatened or Endangered species lists are at risk primarily because of non-indigenous species.”
Here’s a look at a few of our worst regional offenders.
- Japanese knotweed. Take a walk along the banks of the Susquehanna River in the Kirby Park natural area and you’ll see how knotweed has claimed massive amounts of the riverbank. And every year it gets worse.
Knotweed was introduced to the U.S. from Japan as an ornamental, for fodder and erosion control in the late 1800s. It now occurs in 40 states.
It spreads quickly, forming dense stands that exclude native vegetation. On riverbanks, it easily survives severe floods and rapidly recolonizes, usurping the role of native species.
This is one very bad boy: It can grow through walls, tarmac and concrete and can grow by up to four inches a day during the summer. It is listed as one of the world’s 100 worst invasive species. Mortgage lenders have even been known to refuse mortgages on properties which are affected by Japanese Knotweed.
It is tremendously difficult to control, much less eradicate. As Wallace Kaufman says in “Invasive Plants,” “Seedlings may be cut or pulled to exhaust the rhizome and kill the plants. This may take up to 10 years in a well-established stand.”
- Honeysuckle. Ah the sweet smell….and the sour result. Alien honeysuckles tend to leaf out earlier than many native honeysuckles and other shrubs and hold their leaves later into the fall, aiding in their takeover of the land formerly occupied by native plants.
Take a walk along the shores of parts of Frances Slocum Park and just about all you’ll see is Morrow and Tartarian honeysuckle — both aliens — and dogwood lining the shores, to the exclusion of everything else
Additionally, researchers found increased nest predation of robins using alien honeysuckle as a result of plant structure which provides easy access to nests by predators such as snakes. While the fruits of exotic honeysuckles provide some nutrition for birds, they do not compare to the lipid-rich fruits of native species that provide greater energy to sustain migrating birds.
Amur honeysuckle, one of the invasives, was brought to a hothouse in Canada in 1896 because of its attractive flowers. For a time, the U.S. Department of Agriculture even promoted its use for wildlife and as a shelterbelt.
Since it’s so widespread, any control is problematic. In areas where control is possible, shrubs can be pulled or dug out of the ground repeatedly in spring and fall but it might take up to five years to take effect.
Native honeysuckles can be told from aliens by their stems. Natives are hollow while alien stems are a solid white pith.
- Ailanthus (Tree of Heaven)
Having tried to stop one ailanthus from growing near my house, I can testify how hard it is to kill the Tree of Hell. It was called Tree of Heaven in its native China because it grew out of rocks on mountain heights where other trees would not grow.
It is notorious for its ability to grow in hostile environment, from pavement cracks, to vacant urban lots to mounds of garbage. Its tenacity is such that in the best-selling “A Tree Grows in Brooklyn,” it is the symbol of a poor family’s hopes and aspirations.
It first reached the U.S. in Philadelphia in 1748, introduced by a gardener. Then nurseries on the East Coast sold it because it was pest free, grew quickly and, as we know all too well, will grow just about anywhere.
It’s so tenacious because it sends up many root sprouts, rapidly forming a dense colony and it releases chemicals from its roots that hinder the growth of other plants.
Eliminating it is difficult. It can also be dangerous. Its sap contains quassinoids, chemicals that have caused heart problems and blinding headaches in some people who don’t protect themselves from exposure when cutting or handling the trees, according to the Annals of Internal Medicine.
- Garlic Mustard.
This plant stinks in more than one way. Sure, it stinks when you crush its leaves.
But it also stinks because of its unique two-year lifecycle, which gives it a leg up over native plants.
Seedlings germinate in the spring and form into basal rosettes (pictured) by midsummer. Immature plants will overwinter as rosettes that stay green and continue to photosynthesize during periods when temperatures are above freezing – giving them a head start over native plants.
Along with that, it’s “allelopathic”: It releases chemicals that suppress native plants, especially spring wildflowers. It also inhibits the growth of fungi important to many native plants that use the fungi to obtain nourishment from the soil.
It was introduced to America by European settlers in the early 1800s as a food because of its availability in early spring and its high Vitamin A and C. Leaves were boiled in soups and eaten in salads.
Controlling it? Get ready for a war, not a single battle. According to Michigan State University’s Extension Service, “Any control method selected must be repeated for several years until residual seed from previous year’s plants has germinated. To a gardener, this could be a long time. Smaller garlic mustard infestations can be controlled with a watchful eye and rigorous hand pulling during spring before other vegetation greens up.”
- Purple loosestrife
How are you going to fight this?
According to “Invasive Plants,” “Loosestrife’s prolific seeding, its tolerance of a wide variety of water regimes and soils, its ability to produce as many as two million seedlings a season, and its reproduction from broken pieces has allowed it to spread across the continent and outcompete many natives.”
It’s also expanded to the retention basin outside my Swoyersville home, the site of the loosestrife photograph.
If you go into any damp areas around here — such as some of the sunny banks of the Susquehanna — you’ll be blinded by its purple blanketing of the landscape. In some places it has replaced 50 percent of the native species.
Purple loosestrife easily occupies new areas, creates narrow waterways and disrupts aquatic habitats. It also quickly eliminates native plants, such as cattail, which plays important role in the nesting of waterfowls.
Scientists believe that purple loosestrife conquers up to 100,000 acres of loosestrife-free wetlands in the United States every year.
An arrival from Europe in the ballast of European sailing ships, it arrived in colonial North America with the first settlers. Horticulturists later imported seeds for gardens. By the early 1800s it was so common some botanists considered it native.
Control it? Not likely: To date, no effective means exist to eliminate large, established stands of purple loosestrife.”