I've taken it upon myself to maintain the ditch area in front of our house. I haven't weed-wacked it at all this summer because it was so hot and dry the growth wasn't very heavy. I was out there yesterday when I spotted what I think are native blackberry vines. Some people call them "wild mountain blackberries", but that's a bit inaccurate because they don't just grow in high elevations. I remember as a kid growing up in the northern burbs of Seattle in the late 50s, 60s finding large patches of these. I'm glad now that I neglected the ditch all summer, they probably wouldn't have taken root. They're definitely not boysenberry vines, which are a non-native invasive plant with very thick vines (but they produce large yummy berries.) I googled "blackberry vines" and sure enough, the "blackberries" in most of the links refer to boysenberries, not the native blackberries.
http://www.differencebetween.n...
There are three small vines ranging from about 2-5ft long. I discovered them when I was planting some creeping jenny along the bank of the ditch. I fed them some generic liquid plant food. Maybe I'll move the CJ so it won't smother the vines. The ditch picture was taken during the monsoon season last February.