Monday, October 15, 2007

Plant ID: Rhamnus cathartica

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.
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.

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