I have given up trying to id my Rubus (blackberry) species. That said, blackberries are a major source of food and cover for many organisms with whom I share my little patch in the woods and I have a hard time blackberrying because there are never any left! So I am disinclined to remove the brambles willy nilly. However, I spend most of my time here in northern VA removing invasives and if these blackberries were of the non native, European or Asian variety I would reluctantly remove. I read that there are some instances of R. armeniacus, R. pascuus and R. laciniatus in VA but I think they tend to be nearer DC. Someone told me to check the back of the leaves because they said white on back of leaves indicated non native. Does anyone know if this is a reliable characteristic to distinguish native from non native? Thank you!
"Rubus, especially the blackberries, presents some of the most difficult species-level problems, because of polyploidy, apomixis, and hybridization. As a result, differences of opinion on the number of species to be recognized from a given region can vary tremendously" Rubus in Flora of North America @ efloras.org
Yes, that’s my problem! I have researched Rubus into the ground. I have what I consider to be the bible of Rubus species in my area….it is an old volume and probably the genus was split into too many species in this study but the Davis’ study on Rubus in West Virginia is a wonderful compendium on the subject. I realise that I could be looking at hybrids but I tend to think not because I have numerous populations around the property that appear to me to be similar. I have Rubus that I can group into at least 3 different species/varieties. Their form defines them. One has huge leaves, pubescent on both sides, very few prickles and prefers to grow in shade. Another grows erect but then drapes itself over neighbouring plants, has small leaves annd flowers, lots of prickles and a third is simply erect, prefers full sun, I am guessing this one is R. pensylvanicus. I have several populations of each form so unlikely that I would have similar hybrids in different locations? I believe they are all native, maybe hybrids but hybrids of native Rubus. So my question is, if they were hybrids with European/non native species could they have leaves that are not white on the underside? But if so wouldn’t I be finding at least one population of Rubus with white undersides nearby which I haven’t as yet? I have read a lot about growth behaviour of R. armeniacus and I am not seeing this in my blackberries…in fact I find that rather than smothering all neighbouring vegetation, they are protecting young trees from deer…I actually have a mature Ulmus rubra growing in one of my Rubus patches…this tree should be all over the place but due to deer browse I have very very few. Thank you for your input Ron. I guess I’ll just keep the Rubus until someone can tell me definitively that I am growing something invasive. The good thing is that these plants do not have great germination from seed…maybe because they are hybrids or maybe they just need a couple of yrs stratification. So they really are not spreading to neighbouring Appalachian woodland which is my main concern…I spend a large part of my day removing R. phoenicolasius from the woods but I rarely come across blackberries.
