Invasive, nonnative plant species have long been a problem in New York and elsewhere, with environmentally conscious organizations such as the Long Island Native Plant Initiative, agricultural extensions across the country, and yours truly advising against their use for years. Yesterday, Gov. Andrew M. Cuomo took things a step further and actually signed a bill into law that will make it illegal to sell, transport or even possess harmful nonnative plants (and animals) in the state.
Say you take a tropical (or European or Asian) vacation and fall in love with a plant you've never seen before. You're tempted to take a cutting, bring back some seeds or even a whole plant. The plant seems perfectly behaved — it's not taking over the garden where you spotted it, and boy is it pretty! So what's the harm?
The problem is that you don't know how the plant will grow in your home environment. Climate variations, and the absence of insects, diseases and animals that naturally keep its population in check in its native region can allow it to run rampant here. Once here, you may find it takes over your garden bed, chokes out your favorite perennials and even spreads to your neighbor's lawn.
What's worse, many nonnative plants are even sneakier than that: They mind their manners in your garden, but wind blows their seeds far distances and the birds take a nibble and "drop" the seeds elsewhere, including on the water front, where they take hold and compete for space and nutrients with the native plants there. Soon, native wildlife loses its food supply because the greedy offsprings of your prized exotic plants overpower it, and now the animal food chain becomes disrupted, too. Small critters that eat the insects that need the native plants become weak, their numbers dwindle, their predators are faced with a smaller food supply and so on.
Native plants are plants that belong here. They originated here and grow naturally. The benefits of growing natives are many: They're part of the food chain so they help our wildlife, they don't need supplemental irrigation once established and they don't become invasive. Oftentimes, it's hard to tell which plants are natives at the garden center because they aren't usually labeled as such, so even well-informed and -intentioned eco-conscious gardeners could plant them.
In recent years, it was discovered that some plants native to our area aren't doing so well, largely because of the proliferation of nonnative species. Research on local plant biodiversity, conducted by the Brooklyn Botanic Garden and reported in 2010, found at least 50 varieties of native plants are extinct in the area or nearing elimination. Nuttall’s mudflower (Micranthemum micranthemoides), scarlet Indian paintbrush (Castilleja coccinea), pennywort (Obolaria virginica), sidebells wintergreen (Orthilia Secunda) and sundial lupine (Lupinis perennis) are among the wildflower species to have seriously declined in the region, and black crowberry (Empetrum nigrum) is locally extinct, without a trace of a population remaining today in the metropolitan area.
Meanwhile, “a number of invasive species introduced from distant areas, with climates similar to ours — such as parts of Asia, Europe, and the southeastern United States — are newly thriving in the New York area,” according to Dr. Gerry Moore, director of science at Brooklyn Botanic Garden and coordinator of the New York Metropolitan Flora Project. “Camphor weed, native to the southern United States, is common in Brooklyn now; however, at the time of the Garden’s founding a century ago, it was considered to be quite rare.”
Some nonnative cultivated plants, such as Japanese barberry (Berberis thunbergii), can "escape" from cultivated landscape and dominate natural areas. Like many other nonnative species, it thrives and spreads aggressively outside its natural range and can be particularly invasive when introduced to a new habitat. And the damage doesn't stop there: When different plants take over an area, the entire ecosystem can be at risk, as insect and animal life can be drastically affected, as well.
In addition to Japanese barberry, my guess is that purple loosestrife and Japanese honeysuckle will make the list, and "running" bamboo might, too. In addition, aquatic plants like water chestnut. But I wouldn't worry about losing your daylilies: not all natives will be banned -- just those deemed harmful.
The Department of Environmental Conservation and the Department of Agriculture and Markets is required under the new law to identify harmful species and publish a list by September 2013. An interim list is available on the DEC website (http://www.dec.ny.gov/animals/65408.html) but it's important to stress the plants mentioned may or may not fall under the law. Those who possess or transport them first will receive a written warning. Further violations will incur a $250 fine, with vendors facing fines up to $2,000.
Invasive plants are certainly a problem — and have been for quite awhile. Because of the destruction they have been shown to cause, I agree it should be illegal to sell them and bring them into the country or across state lines. It's still unclear, however, how the law will pertain to residents who unknowingly have those plants in their gardens, having purchased them legally. Many homeowners don't even know the names of plants growing on their properties so I can't imagine that publishing a list of banned plants would be sufficient enough to hold them accountable. This will be interesting, and I'll be sure to keep you posted as details surface.