November 18, 2012

A Bittersweet Tale

Even after most of the leaves have fallen from the trees, late fall has a lot to offer in the way of color and interest. Recently we noticed these bright berries on a walk in a nearby park:

I recognized them as the fruit of a woody vine called bittersweet, which is often used in fall wreaths and other decorations. I hope that this particular plant is American Bittersweet, Celastrus scandens, but I suspect that this plant is its extremely nasty cousin called Oriental Bittersweet, C. orbiculatis. Without leaves they are hard to tell apart on a small plant, but the oriental variety tends to have fruit all along the twigs rather than just at the tips. 

What's so nasty about Oriental Bittersweet? It is one of North American's most invasive plants. Its seeds are readily spread by birds, and their germination rate is very high. The plant grows rapidly and can engulf large trees, out-competing them for sunlight. The really menacing thing about these vines is that they can grow up to 4 inches in diameter and can literally strangle a large tree by compressing its vascular system and preventing the flow of water and nutrients, much like the tropical strangler figs. Here is a picture of the plant that we saw, showing a small woody vine climbing in a twisting fashion up a shrub:

Imagine a 4 inch vine doing the same to a large tree! 

A few days later we were taking a walk in another park and spotted something I'd never seen before: a small tree with what looked like bright pink berries:

I knew it wasn't familiar so I had to take a closer look:

Getting even closer, I saw that the fruit was actually red with a pink covering, and it certainly had a structure similar to the bittersweet we had seen a couple of days before:

A bit of googling and checking in some books soon revealed the plant to be a small tree or shrub called American Wahoo (Euonymus atropurpureus). It too has an invasive cousin, E. alatus, which is the common landscape plant known as burningbush

According to Horticulture Magazine, American Wahoo is an excellent choice to replace E. alatus in the home landscape. "Once the foliage drops, the red fruits inside light pink capsules will stop traffic." It certainly stopped me! It is native to the eastern half of North America, and is generally found along streambanks but can do well elsewhere also. American Indians believed it to have a "warrior spirit" and planted it around their camps to keep enemies out.

So back to the fact that both bittersweet and American Wahoo have bright fruits which are revealed with the opening of a colorful capsule. Well, a bit more research reveals that both plants are members of the botanical family called Celastraceae, or the bittersweet family. Most of the genera within this family are tropical, with Euonymus, Celastrus, and one other being the only ones to grow in temperate areas.

Both American Bittersweet and American Wahoo are interesting plants to find when hiking in late fall. Both can be fun additions to the home landscape as well. Just be sure to avoid the nasty relatives! (Always good advice as Thanksgiving approaches...)


  1. Love the bittersweet humor about invasive species and avoiding nasty relatives at holiday time. Very interesting piece...I had no idea that there are both "okay" bittersweet and invasive bittersweet.

  2. I just saw berries like the top bitterweet ones, but I didn't know what they were. I also saw a very interesting, distorted tree trunk that had managed to out-survive being strangled by some sort of vine that was no longer present. Now I am wondering if it had a close encounter with oriental bittersweet.


  3. I just posted a photo of my Bittersweet berries on Flickr ( I think they are the Oriental ones because the berries were all along the stem. Too bad it's invasive. :(