ORNAMENTALS GONE WILD – – Invasive Oriental Bittersweet on Presque Isle

November 20, 2012 7:49 am Published by Leave your thoughts



Oriental Bittersweet Vines on Presque Isle – – E. Ware


     It all started quite innocently when greenhouses imported this vine for the value of showy red arils that serve as covers for its seeds.  This was back in 1860.  Even today, they are still popular for use in flower arrangements and wreaths…  While the vines and their little red berry-like arils seemed harmless, they soon began to show all the traits associated with problem invasives.  The real problem with this bittersweet is that birds soon found the seeds attractive and began to call them lunch.  Of course, this quickly spread the vine, and it escaped controlled cultivation.  Once out in the wild, it began a rapid and un-contained spread.  Today it can be found growing rom Florida north to Maine and now as far west as Missouri. 

Large Vine

     Once this vicious vine becomes established in an area, it out competes nearly all other plants it comes in contact with.  It even hybridizes with native bittersweet, and the resulting offspring becomes an almost perfect Oriental Bittersweet killing off the indigenous plant’s traits.  As you can see from the pictures in this blog, this invasive is not what most people would classify as an ordinary vine.  Yes, it can be pretty, and yes, it can bring down a 60-foot tree on Presque Isle.  It is like a hired assassin.

This bittersweet can grow more than five yards each year.  With a growth rate like that it can easily reach the canopy of the tallest forest trees within just a few years.  The biggest problem is that as it grows, and by the way the vines get huge, it girdles the trunk and can actually kill branches of its host as it moves up the tree.  When it hits the top of a small tree, it can and does reach across to nearby trees and continue its journey.

Another problem is that it blocks sunlight to the host trees, and prevents the trees photosynthesis and can cause them to die.  On the park, I have seen the sheer weight of this huge vine topple large trees when Presque Isle winds blow through an area.  I have seen three foot in diameter destroyed by vines that have grown to six or more inches thick.  On Presque Isle, this invasive is becoming truly out of control invasive.

Vines moving from tree to tree

What this vine does to young trees is insidious.  Like many invasives, it loves to grow in the full sun.  This means it can be found in areas where fields are in the process of returning to forests.  The bittersweet grows at three to four times the speed of most trees.  This sets up a problem when young trees begin to grow in the open field or along their edges.  Once the small trees get a start, birds find them a handy place to perch, and as a result, they deposit Bittersweet seed at the tree’s base.  These seeds soon germinate, and usually with a year or two, the vines smoother and kill the tree.  

The park staff and a few volunteers have been working to keep this killer at bay.  Yet many of us feel this is becoming an impossible task.  Unlike many invasives, spraying and other easy methods of control are at best a waste of time.  These are huge vines and they must be treated with methods that are more forceful.  It is the hope of many of the park’s regular visitors that the effort to control this dreadful invasive will continue and expand.

Vines on nearly dead tree – – E. Ware




See you on the park!


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