Several sources state that there exists a considerable diversity of blackberry brambles in northwestern Europe:
Wildlife of Britain (ISBN 978-1-4053-2932-3), p. 366: “… this species is divided by some botanists into hundreds of microspecies, but they all look very similar.”
Food for Free (ISBN 978-0-00-718303-6), p. 41: “There are reckoned to be at least 400 microspecies in Britain, all differing slightly in flavour, sweetness, fruiting time, nutritional content and size.”
I’ve certainly noticed a diversity in local brambles on any given walk, with differences in flowering time (some only start developing flowering buds while nearby plants are well into the fruiting stage), leaf morphology (some are trifoliate, others have five leaflets in a palmate arrangement, and there are often intermediate leaves in which the lower smaller leaves are fused into the larger leaves above them, resulting in what I like to call a “butterfly” arrangement), and other subtleties. The question at hand: how exactly would I determine what exact species a given bramble may be classified as? Are there any good resources that can be used, particularly beginner resources to start with, that can assist here?
Of the blackberry canes that I’ve identified, I’ve marked down two so far which I believe may be the invasive Himalayan/Armenian giant bramble due to thick canes, large palmate leaflets with long spiked petioles, and pale whitish leaf undersides, but even then I’m not 100% confident in these identifications. As for the smaller native blackberries, I can’t decide where to even start. Clearly, unlike with the carrot family, there is little need to distinguish between different species as all fruits in the bramble family are edible and not inherently dangerous to consume, but this desire to more fundamentally understand what exact kinds of bramble populate the local area refuses to remain unsatiated.
If we were discussing tomatoes, those would be cultivar-level differences. Why should wild plants be assumed to be uniform when they are capable of so much variation once cultivated?
The thing with members of the European Blackberry Complex is that they set seed apomicticly (without sex). Therefore, a population derived from seeds and covering a large area may be a single clone. It looks like a species because it’s growing alongside another clone that differs from it a little bit in several traits. That’s the kind of consistent, multitrait difference we’d like to treat as a species. And there’s a third clone. And a fourth. Etc. All a little different. Lots of “species.”
These all do have sex occasionally and produce seed from these unions. If the parents were different clones, these offspring are a little different from both – they are hybrids – and they can form a new clone that spread over a large area while retaining their traits, their differences from the other clones around. They seem to be behaving like distinct species.
As you can see, I’m not fond of treating all these different members of the European Blackberry complex as species. But there is a lot of variation in the group. Some of these variations help the clones adapt to different environmental conditions. Some differences look worth treating at the species level. But if you start dividing the group up, where do you stop splitting? This is a crazy-making situation for botanists.
I think that anyone should start relying on the help of a batologist experienced with the bramble flora of a specific area/country. Otherwise it is extremely complicated to get into this genus.
I disagree that this is “behaving like distinct species.” Returning to my tomato example, you can have two cultivars that come true from seed, and when they cross-pollinate, the offspring are a little different from both. Now, there is a difference in that you are referring to apomictic seed set; but the occurrence of viable cross-pollination shows that there is no inherent barrier to reproduction between genets.
Where is the line between cross-pollination between cultivars (or genets) and hybridization between species? From the tiny ‘Yellow Pear’ to the big ‘Black Beauty,’ tomato cultivars show variations in size, color, flavor, adaptability to specific environments, disease resistance, and even the major division between determinate and indeterminate. How is this different from the blackberry situation, other than that the blackberries have the added capability for apomictic seed set, which is not even obligate?
Sorry. I was unclear. I meant, SUPERFICIALLY those clones look like species. Same can be true for cultivars. But actually, they’re not good species, in my opinion, though lots of them have names.
Brambles of the British Isles by ES Edees and A Newton was published by the Ray Society in 1999. The book is out of print but there is a version on cd produced by Pisces Conservation, £45 from NHBS. Unless you are going to devote a large part of your natural history time to brambles, I wouldn’t get it. It isn’t a subject you can just dip into. Most county botanists in Britain don’t tackle brambles, they wait for a specialist to visit their county.
Except for Rubus ulmifolius, which does - it can then hybridise with the apomictic ones, just in case the group wasn’t annoying enough.
For the UK at least there are a couple of clearly very different species - there’s a few that can easily be told (the “Himalayan Giant”, Rubus armeniacus is pretty distinct once you learn to recognise it, Rubus laciniatus has uniquely cut leaves like no other bramble, the dewberry is very small and low-growing and the only one a white, waxy sloe-like cover on the fruits).
Otherwise they’re quite different but clearly go beyond ‘just cultivar level’ - a wander looking at brambles will show you lots of variation, like size, hairiness of the canes (including glandular hairs), growth habits (some sprawl, some climb), flower colours, habitats (e.g Rubus sprengelii likes heaths), prickles (angles, placement - whether they’re on the angles of the stems or all surfaces), their colouration (e.g Rubus armeniacus usually has a red tint at the base), stem colours (some go red in sun, others don’t).
I think they’re more like dandelions in that respect - clearly a lot of variety, sometimes has clear ‘groups’ that have certain preferences (most of the weedy dandelions are meant to be sect. Ruderalia), but I can rarely be bothered to do more than plonk them at complex level because barring the aforementioned three most of the times I try to work it out to a species I end more confused than I started :)
Since blackberries are now fruiting I’ve noticed some variation in the fruits as well - there are some which fit just about every expectation for dewberries, except the fruits are lustrous like “normal” blackberries are, rather than covered in the glaucous, waxy bloom I’d been conditioned to expect for dewberries. Perhaps a mostly-dewberry hybrid, or simply an expected intraspecies variation in R. caesius? I have picture examples on the main site for anyone interested.
There was also a R. armeniacus candidate or two I uploaded, but again I don’t have access to any plants that I know for sure are that specific species so a lack of reference point doesn’t do anything good for that assertion. Encountering a plant in-person goes much further than even hundreds of picture examples so I hope I encounter something unmistakable one day, as invasive as it may be,
I have seen some of your OBs attributed R. caesius and they are not R. caesius. Rubus caesius have very few, large, pruinose drupelets. I can say that these OBs do not depict the diagnostic characters (for example the stipules on the sterile suckers). Among the brambles that are somehow similar to R. caesius there are the so-called “Rubi Corylifolii” which are very numerous and, of course, difficult.
I do not want to discourage you. If you are very interested in this topic, you will surely be able to obtain good results. I still think it would be useful to get in contact with local researchers to get more insight.
I’ve been told that R. armeniacus is a common pest species, but reviewing the three or so I’ve uploaded to the site under this species name makes me less sure that what I have is indeed that species. Is it simply more concentrated in England and coastal North America? There are five leaflets in each of the ones I’ve found, with large leaves overall, and thick stems, and the undersides are much whiter than other blackberries, but much like with the dewberry case I can’t be certain if this constitutes a conclusive identification.
Rubus is one of those taxa that doesn’t fit the species complex very well, along with Crataegus, Quercus, Salix, Taraxacum, etc. This is where it would be nice if iNat could innovate and create a more flexible ID or taxonomy framework with lumped ‘species’ and maybe split out ‘microspecies’ or some other subspecies like entity. Unfortunately people on here are very fixated on remaining loyal to the broken academic taxonomic system, so there honestly isn’t much hope in identifying beyond genus for a lot of these, or perhaps section/species group in some cases. What would be ideal would be a way to describe and document this wonderful spectrum-based organism population, but maybe iNat just isn’t the tool to do that. Maybe nothing really works within the capacity of humans, I don’t know.