Rosa multiflora is a common roadside weed around here, and generally doesn’t get much of my attention, but I was walking along, I noticed something very strange – in among the bright green new growth of a large R. multiflora growing beside the road, there was a single cane that was a deep burgandy-green color. Looking closer, I found that wasn’t the only difference – the leaf edges were much more serrated, the leaflets much longer and narrower, and the stipules have an almost feathery edge. I am pretty sure the thorns are also smaller, thinner, and more plentiful. Here is what makes it still stranger: Walking around, I have now noticed three other R. multiflora bushes with the same apparent mutation. Three of the four plants I’ve found it on only exhibit the odd shapes and colors on a single cane – but oddly, it is a cane which grew last year, and is now producing secondary growth – and I could SWEAR there weren’t any canes like this growing last year. The fourth is a R. multiflora I cut to the ground last year in an attempt to clear out an overgrown area. I meant I come back and dig it out, but never got around to it. Now it is coming up – with all of the new growth the odd color and shape. There are several other plants right next to it which got exactly the same treatment, but look normal.
So, what’s going on? At first I thought sport – but why would four (at least) bushes all produce exactly the same sport at the same time? Then I thought it must be a virus, but how could that only show up in one cane? Viruses get passed from rootstocks to scions, so I would assume they would be passed from one cane to another of the same plant. And the strange canes don’t seem to be any less vigorous than the normal growth.
Any ideas as to what on earth is going on? I’ll try to get some pics up tomorrow.