Invasives: Out Of Control


We have become an incredibly mobile society, with ships crossing oceans in days instead of months and travelers able to transect continents in a matter of hours. But this ability to move goods and people quickly has had some disastrous consequences in terms of our health and our ecology.Enter the world of invasives. Be it a germ, a bug, a plant, a bird, a snake or a worm, invasive species are now a part of our everyday life.

The threat of invasive plants has always concerned me and been a frequent topic in this space. The threat continues and quickens, and yet some of us are still uninformed, careless, willfully destructive and sadly misinformed.

A number of weeks ago I received an email from a reader in desperate need of help. She had innocently planted pachysandra around her apartment perimeter as a quick ground cover. Well, why not? It fills in rapidly, tolerates a great deal of shade, needs virtually no care once established, can stay green year-round and it even has nice white flowers that add a color contrast to the otherwise monotone planting.

Then came the letter informing her that the planting of pachysandra terminalis was expressly forbidden by the by-laws of the community. And she was being not only fined but told to rip it out immediately, as it was a prohibited invasive plant.

Oh really?

The fact of the matter is that pachysandra is not considered an invasive species in New York, or any nearby state. That this plant is thought of as an invasive is a common mistake based on some poor documentation. At most you’ll find the state of Pennsylvania referring to it officially as “aggressive,” but not invasive.

In the meantime, not too many miles from where this invasive witch hunt took place, you can drive into the hamlet of Hampton Bays and on two of the main access roads there are very attractive plantings of perennials and shrubs along the highway center median. These plantings are well kept and maintained and provide wonderful color and softening to an otherwise concrete and blacktop viewscape.

But what’s this among the ornamental grasses, rudbeckias and spring flowering magnolias? What are these purple flowering spires of early summer that attract butterflies for weeks on end?

Can it be lythrum salicaria, also known as purple loosestrife?

The dreaded invasive is outlawed for sale in several states and is named as an invasive species in just about every state in the union. Can it be that right here in the Hamptons, such a plant that has doomed so much wetland area is being grown and cultivated on public land by a civic organization or a local municipality?

It can’t possibly be true. But sadly, it’s been going on for years and years.

Most garden centers don’t even sell it anymore. But here it is, an ecologist’s nightmare, being cultivated right at the entrance to Hampton Bays.

Pachysandra and lythrum are really old news. We now know the truth that pachysandra is at best a marginal threat, and we also know that few are now planting lythrum. But there’s a new kid on the block. Actually, a few new kids.

You’re probably well aware of the weed, garlic mustard. It’s actually neither garlic nor mustard but a biennial in the mustard family.

In its first year of growth it sprouts up in the garden, in the woods, just about everywhere, with some innocuous leaves that can easily be overlooked in the garden. It overwinters as a few leaves in a crown near the soil, and then the second year it starts growing like a rocket and spikes for the sky.

The plant elongates and can grow from a foot to 3 feet tall, producing tiny white flowers. Those tiny white flowers turn into 3-inch-long seed pods that soon explode, sending thousands of garlic mustard seeds 5 to 15 feet from mama.

Now this wouldn’t be so bad if only the deer would eat this plant, but oh no they won’t touch it.

The following spring, thousands of garlic mustard plants spring up. They grow some leaves, then hide until the next year when they go to seed, producing hundreds of thousands of seeds. In just a few years, your entire landscape from the perennial border to the woods becomes carpeted with this plant.

This weed outgrows all our native plants in seed production and persistence so once it gets out of control, it’s out of control. Within 10 years it can decimate all the natural ground cover in a woodland or wetland. And yes, it is listed in most states as an invasive species.

Thankfully it pulls out easily, and with some persistence it can be eliminated from the landscape simply by pulling it out before it goes to seed. But leave just one plant behind and in no time at all you’re back to a garlic mustard ground cover.

Then there’s Japanese stilt grass. It’s been around since the early 1900s, as it was used as a packing material for goods shipped over from Asia.

It found a very welcoming home here in America. Slowly but surely the seeds from the packing material hit the ground, germinated, and this invasive now is a threat east of the Mississippi River, from the Gulf up into lower New England.

It’s an annual grass but it’s so prolific that once in an area it drops seed and spreads or colonizes entire ecosystems, including woods, wetlands, gardens and open fields. It tolerates a multitude of soil and light situations and it very quickly chokes out native plants of all kinds by “out competing” (growing faster and seeding more prolifically) everything else.

Early control is important. Once it’s discovered, like with the garlic mustard weed, persistent pulling in the early stages of an invasion can mean the difference between gaining control and losing it.

There’s a great new initiative to bring together all the various efforts at invasive species education and control that hitherto have been woefully disorganized. In New York, this is being done via new regional cooperatives. Get a great start by visiting the New York Invasive Species website at and doing some reading.

Do your part to help. Don’t grow invasives. Get informed. And keep growing.

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