Plant ID: Lysimachia clethroides (A Discussion on Potential Invasives)

Gooseneck loosestrife (Lysimachia clethroides) is a member of the primula family, Primulaceae. It is native to China and Japan, and therefore is an introduced species here in the United States. It has upright stems with long, narrow foliage that are 3” or 4” in length. The plant grows about 2’ to 3’ tall and spreads by fast-growing rhizomes as well as by seed. In late summer the plant produces spires of white blossoms right above the foliage that grow in beautiful curvy and contorted forms, hence the name. Gooseneck loosestrife grows in full sun to part shade and is adaptable to a wide range of soil conditions. It is hardy in USDA zones 4-9. But beware, just because it sounds and looks like a beautiful plant does not mean you shouldn’t still do your homework.

I was first introduced to this plant when I found it growing outside of my father’s retail shop in the Hamptons years ago. Next to a formal herb garden that I planted outside the storefront window was an unkempt space and in it was growing gooseneck loosestrife. My father enjoyed the plant, its persistence, and late summer flower, so we left it in the area and let it do its thing. In fact, when my father closed the shop he liked the plant so much that he divided a piece from the mother plant and transplanted it to my parents garden at home.

If only I knew then what I know now.

After a few years my father called and explained that the loosestrife was quickly taking over my parent’s garden and asked how he might control it. We talked about the multitude of small black seed that follow the profuse spires of white flowers and I recommended deadheading the flowers before they passed maturity to prevent the seed from forming. I also taught him about the aggressive underground rhizomes and explained that he would have to remove them entirely to ensure that the plant did not come back. Lastly he asked if he could move it to the other side of the driveway, which happened to be adjacent to a portion of natural woods. I exclaimed, “No, you can't do that!” Plants that become invasive in home gardens are bad enough, but when they spread to natural woodlands then the problem can become exponentially worse practically over night. Had the gooseneck loosestrife been allowed to drop seed and spread it’s rhizomes into the woods then there would be nothing holding it back. As an introduced species with no natural predators, whether they be other plants, feeding insects, or diseases, the plant would eventually begin to overtake our important native plants, ferns, and mosses. It sounds hard to believe that one transplant could disrupt an entire ecosystem, but unfortunately I have seen it happen entirely too many times.

Burning bush (Euonymus alatus) is perhaps one of the best examples. Originally chosen and planted in American gardens because of its brilliant red fall color, burning bush is an introduced species with no natural predators. Planted in suburban lots all over the northeast the seeds eventually spread into nearby woods and began to produce multiple seedlings. Now, from southern New Jersey to northern Massachusetts natural forests and woodlands are being disrupted and native species are losing the fight against this invasive shrub. Driving in the fall you might not think anything is wrong as you see patches of the bright red shrub amidst your local woods, but a trained horticulturist will be quick to tell you otherwise. Organizations devoted to restoring natural ecosystems and habitats can no longer attempt to eradicate the problem and the plant populations that have run rampant; the best we can do now is to control the infestations as best we can. Some states have made great strides to make invasive plants illegal to buy or sell, but I am sorry to say you can still find burning bush for sale in New York State.

You can tell this is a topic I feel strongly about. Therefore you can imagine how my emotions flared when a woman called recently to ask about how she could get rid of a patch of gooseneck loosestrife in her garden in New Jersey. I explained the profuse seed production and the aggressive rhizomes and she knew the characteristics all too well. Year after year she dug up as much as she could, even resorted to Round-Up, an extremely strong chemical herbicide that should only be used as a last resort, and still she would find new growth every spring. I believe she said it is now the fifth year of her battle. I tried to find feeding insects that she might introduce to her garden that would target the gooseneck loosestrife, but to no avail. There are more heavy duty herbicides on the market, but in a condensed residential neighborhood I could not ethically recommend introducing them for fear that if wrongly applied they might leach into the ground water. After much research and many conversations it was frustrating that the best piece of advice I could give her was to not lose hope, to keep up the fight, and to reaffirm that she was doing everything right.

So, what lessons can we learn from these overwhelming tales? While conservation and native plant advocates fight for stricter policies regarding the growing and sale of invasives, (insert applause here), it is our duty to be the best educated consumers we can be. Gooseneck loosestrife, to the best of my knowledge, is still not considered invasive. I even found a few websites that listed it as an “ideal garden plant”. Obviously I beg to differ. The next time you see a plant at the nursery that you are new to, consider doing a little research before taking one home and planting it in your garden. If it is an introduced species from another country, even if it has been introduced for centuries, see if you can find out if it has any tendencies towards becoming invasive. In this regard a little internet or book research can be invaluable for the long run. Better yet, see if there is a native alternative that might work just as well in your landscape plan.

Plant ID: Rhamnus cathartica

Question:

I have a large row of bushes/shrubs that are at least 10 feet tall and I haven't been able to identify them. They seem to be common in my area (central New York) since I frequently go for walks around the Erie Canal and see them everywhere in the wild. I would like to plant some more since some of the hedgerow has been taken over by vines and the bushes have died. The leaves on the branches are directly across from each other and each leaf has jagged edges are are oval shaped with a point on the end opposite the stem. The veins on the leaf start down at the base of the stem and go up following the shape of the leaf and the veins are identical on each side of the leaf. In the fall this bush produces berries that are black/deep purple in color. I have included pictures. Could you please help me in identifying this? I've done a search on the internet and haven't been able to come up with anything.

Answer:

Thank you for writing. The shrub you are trying to identify is Rhamnus cathartica, commonly known as common buckthorn. This shrub is native to Europe and western and northern Asia. As you have discovered on your walks, this large shrub has a dense, rounded growth habit and can get as large as 18’ high and wide. The glossy dark green foliage is 1 ½” -3” long and almost as wide, with an acute tip and finely serrated edges. In the fall common buckthorn bears in clusters these ¼” black fruits, technically called berry-like drupes. Common buckthorn is cold hardy in Zones 2-7, which means it can live most anywhere between New York City and colder points much further north.

Even though the shrub has some attractive characteristics, I must deter you from searching for or planting this shrub as it is considered invasive. According to the USDA website, common buckthorn is considered invasive and/or banned in Connecticut, Massachusetts, New Hampshire, and Vermont. I was not able to find information pertaining to the status of this plant in New York, so I would go ahead and steer clear of it to avoid potential fines or danger to your local environment. I am not sure how familiar you are with invasive plants, but here is a little more information as to how this shrub has become classified as such.

Over the past centuries, plants from other continents have been introduced to North American landscapes because they were considered beautiful and viable in our climate zone. Common buckthorn, with its dense habit, glossy leaf, and black fruit, is a perfect example. Norway maples (Acer platanoides), burning bush (Euonymus alatus), and purple loosestrife (Lythrum salicaria) are other examples of invasive species in the Northeast. They were planted, they did well, continued to grow and produce flower and fruit, and spread throughout the landscape. The problem, however, was that people did not think about how they might have to eventually control the plant’s populations. Because it is from another part of the world, predators and/or insects that feed or do damage to the plant do not exist, nor are there other plants that grow as quickly and aggressively to naturally compete with the buckthorn. This is how introduced plants can then become considered invasive. The plant was left loose in the wild for long enough and continued to spread, and now it is overtaking native plants and natural habitats. This leaves us having to turn to nature conservancies and habitat restoration advocates to come in an attempt to undo decades of wrong-doing. And I can speak from personal experience that it is the most admirable work and yet the most overwhelming and greatest challenge ahead of us as horticulturists and stewards of the land. Just in your area think about how much invasive buckthorn there must be. We must always be careful of introducing non-native plants. It is always a better practice to choose native alternatives instead.

That being said, are you familiar with viburnums? There are many different kinds of viburnum, most of which are North American natives, that can be planted in a row to create a nice full hedge. Depending on the specific species, viburnums may have fabulous spring flowers that can be very sweet and fragrant, excellent variation of leaf shape and size, interesting fruit-set in the fall, intense fall color, or all the above.