Hi, Charlie.
I've been wondering the same thing. I have some plants that have grown into my hedges that look like some of the example photos seen on this website but mine are thorny.
There is a photo on this website showing a plant growing near a fence. It appears to have thorns so I think it's possible.
http://poisonivy.aesir.com/view/picqna.html?func=viewQNA&did=1117&wid=486 |