Hello. I am trying to ID a species of blackberry I have growing around me. I have plenty of R. phoenicolasius, R. occidentalis and R. flagellaris. The area is in northern VA, a stone's throw from W. VA panhandle for anyone who knows this area, and blackberries generally grow at edge of woods (except for R. phoenicolasius which grows everywhere). I don't believe that the species is R. armeniacus as behaviour doesn't match. These blackberries do not root at the tip of the cane and in the 10 yrs I've been observing them they do not spread much, if at all, so patches are well defined and stable. They generally arch to about 5-6ft. However, there are some rogue canes that have reached an upper deck (6ft)and have trailed through railing on deck and well out onto deck. So these canes have become very long indeed! Is there any way to truly ID blackberry species short of some sort of genetic test? I was guessing that the species was R. pensilvanicus but the rogue canes are making me think I'm wrong. Are there any really good resources that I could use or is this a waste of time because it is almost impossible to really ID blackberries?
Rubus in eastern North America have been the subject of much argument, see Rubus in Flora of North America @ efloras.org So, if you want to follow the conservative Flora of North America treatment (the Rosaceae treatment is relatively new, maybe only a few years old), that link above has an identification key.
Thank-you for the link. I think R. pensilvanicus is the best fit except for those few canes that seem to be exceptions to the arching stem description and are now creeping all over the deck!
