Research indicates buckthorn provides a
winter host for soybean aphid in the fall. Buckthorn serves a shelter for
soybean aphid eggs to overwinter. In addition, buckthorn also disrupts the
balance of our natural world pushing out desirable native understory plants,
creating a dark dense thicket. There are a lot of seeds and you might
think these berries are good food source for birds, but the berries are actually a
laxative for birds and are cathartic. Buckthorn starts as a small sprout, but
before you know it it’s a half inch in diameter and 2 to 3 feet tall. In
Minnesota, I’ve discovered buckthorn that’s 10 inches in diameter and 35 feet
tall and into the overstory canopy of the forest. Buckthorn is a well-known
plant I think most of us know is not welcome in Minnesota.
It’s a shrub or small tree that was originally brought over by Europeans in
the mid-1800s for landscaping purposes, but with the help of berry-eating birds
it’s a plant that got away. And, boy, did it get away.
Today, buckthorn thrives in the wild, in the woods, fence rows and farm
shelterbelts. Buckthorn seeds have been known to remain viable for over a decade.
This plant is a survivor. It can even change the soil chemistry, making it less
friendly for our native plants. And here is a great example of an understory
where buckthorn has taken over and the natives can’t compete. There are a couple
of easy ways to identify common buckthorn. It gets its name because at
the end of the twig you see paired bud. It looks like a miniature buck hoofprint.
That’s where you also will find a small thorn wedged between the terminal buds at
the end of the twig. It’s only about a quarter of an inch long,
but those thorns make handling this plant annoying and sometimes dangerous.
The buck print, the terminal buds and the thorn in the middle are the key
identifying feature of this plant. Let’s take a look at the leaves.
They’re glossy, simple and oval, almost egg-shaped,
and have serrated edges like a kitchen knife. Buckthorn grow opposite or sub
opposite on the twig and are some of the first leaves to appear in the spring and
the last to hang on in the fall, giving them another competitive edge of our
native plants. Buckthorn berries are dark purple, almost black, clustered along the
stem at the leaf axle. Berries remain on the plant all winter long, while berries
are only produced on female buckthorn. Soybean aphid overwinters on both male
and female plants. There are some native look-alikes. Cherry is one that’s often
confused with buckthorn. Here you can see the difference between a buckthorn twig
and a cherry twig. No thorn at the end of the bud on a cherry, and it also has
an alternate leaf arrangement. Buckthorn outer bark and leaves are similar to
cherry and plum, so another way to confirm this is really buckthorn: orange
sapwood in medium-sized stems can help distinguish it from our natives. So
remember, the two key features for identifying common buckthorn are the
hoofprint-like buds at the twig ends and the short, sharp thorn. In our next
episode, we’ll be showing you buckthorn management techniques. Be sure to check it out.