On the Maple Society FB page, Piotr Banaszczak posted photos of "Native maple species of Georgia - Transcaucasia". Among them, a species I had not heard of before, and that is still to be confirmed as a different one from Acer campestre, Acer orthocampestre : Log into Facebook
From IPNI: Acer orthocampestre | International Plant Names Index Original publication (open access): https://journals.tubitak.gov.tr/botany/issues/bot-14-38-6/bot-38-6-3-1403-87.pdf
It's also listed by Kew's POWO checklist. Acer orthocampestre G.W.Grimm & Denk | Plants of the World Online | Kew Science I.e., by all right, it is a validly described species :) But an important node: the Causian field maple, A. orthocampestre, is truly a cryptic species, i.e. you cannot distinguish it from it's (evolutionary speaking relatively distant) sister, the common field maple A. campestre, by any (known) morphological means. It can only be identified by its genetics. As far as we can tell, A. orthocampestre occupies in the Colchic region (Caucasus) exactly the same niche than its western counterpart (which maybe even less niched), it's in all aspects that we know of "just" the Caucasian A. campestre. I.e. for horticulturists, it's irrelevant to distinguish them: planting an A. campestre or A. orthocampestre will make visually and otherwise (regarding its requirements to soil, sun, and water) no difference (that we know of). We only found it crucial to discern because as scientist we focus on biodiversity and finding and protecting important genetic resources. If we lose any A. campestre population outside Caucasia, we can easily replace it by the many others. But when we lose the Caucasian field maples, we lose a relatively ancient lineage of (field) maples. Biodiversity wise not different from e.g. losing the Japanese field maple (A. miyabei). PS The Caucasus is something like a storehouse for tree genotypes that were lost elsewhere and overlooked species. For instance, any "subspecies" of maples restricted to that area, is, in reality, a good species characterized by highly diagnostic gene pools (e.g. A. ibericum; usually treated as subsp. of A. monspessulanum) PPS Generally this section of maples (sect. Platanoidea) is currently under-taxonomized, and may include some more cryptic or pseudo-cryptic species (pseudo-cryptic means that taxonomists just overlooked them because they are morphologically not obvious).
Hello, Can you point me at the paper that describes the molecular analysis of A. orthocampestre and compares it with A. campestre? I have heard the maple described qualitatively, by Piotr and in Eastern EU, but I have never seen any phylogenetic analysis, or indeed any formal analysis. I think it's not uncontroversial to call this a separate species, which is why neither the IDS nor the MS recognize it. Though that may of course change. Thanks, -E
The link to the original publication I posted above (11 Oct 2021) is dead now, but it is still accessible via archive.org, here. Worth adding, it may turn out to be a synonym of Acer campestre subsp. leiocarpum (Opiz) Schwerin [syn. Acer leiocarpum Opiz, 1824]. Unfortunately, Opiz does not give the type locality of his species, but it is usually cited as the eastern populations of A. campestre, so it may prove to be the same as A. orthocampestre, and predating it by nearly 190 years.
Thanks for dredging it out, Michael. I'll read over the next days, with interest. Certainly heavy weight authors with important prior work in the area. The herbarium sample looks much like the Hungarian A. campestre v. acuminatilobum, or "Matra Ancient Maple." I don't think molecular analysis has been performed on this one. We grew it for a few years, grafted, it was happy and reached about 2 meters before suddenly dying for no apparent reason.
It may well be but since there is no type locality, and it's a cryptic species, we cannot establish it's the same thing. But it may be worth digging in historical archives to see if the holotype of A. leiocarpum is from the Caucasus. If it is, it'd be (very unfortunately...it's the only extant species we named) indeed a senior synonym. I would miss our name, though, because I like it when plants have names that have a meaning (bleak-/white-fruit). Also this putative subspecies has a very wide range according to POWO, and it's obviously just geographically defined combining various populations that are genetically not distinct as a whole. We called it orthocampestre ("Colchic genotype" in the map above) because genetically it represents the source population of at least its Platanoideae sublineage (the campestre-miyabei species complex), it is absolutely closest to the "last common ancestor" of all Platanoidea, a sort of genetic living fossil. Re any other variety: we included for our study pretty much anything that A. campestre has to offer in leaf shapes and habitats in our sample. The trilobed ones, the ones with the square-cut twigs, the ones with extra tooths. But eastern Europe has been severly undersampled as seen in fig. 6 of the paper (we didn't go there, we only included material from original stands that we had visited). Especially the Balkans may hold some more treasures. We also had no material from N. Iran, which would have been most interesting: the forests facing the Caspian Sea are another of these storehouses of otherwise lost cryptic or forgotten species (e.g. their Oriental beech is definitely a distinct species from the Orient beeches in SE. Bulgaria and NW. Turkey, too; there are now a couple of high-detailed genetic papers showing that). I remember that a former colleague of mine, Roman Volkov (here's his GoogleScholar profile), who then went back to the Ukraine had some more genotyping done some years ago (he's very passionate about these nuclear markers) and noted that A. orthocampestre does extend into the Crimean Peninsula. Not sure, if they have already published those data and results of the Ukrainian maples (he's a genetics professor in Chernivtsi, that's right in the Carpathes, westernmost Ukraine), at least there's nothing in the English publications on his profile. If you have interesting material and you would like to go a bit into genetics, he may be interested. Despite the circumstances they keep on doing what they are very good in (cloning and sequencing these particular markers). What makes this species and its many variants very interesting is that while the (remaining) A. campestre appear to be generally morphologically more variable than those in the Caucasus, they also show a higher intra-species and inter-population diversity than most other maple species at the molecular level, which, giving the continuity of their distribution area usually means, it's more than a species (for example: A. platanoides is genetically quasi-invariable in the same markers across its entire range). With the new next NGS approaches and a good sample of natural stands, it might be possible to carve out even more species like in the beeches. But maples are too ordinary for systematic botanists, so nobody took really on where we stopped. I collected some ideas around on my Res.I.P. blog. Searching for a research object? Why not maples!
Fascinating! A small error in the map; the native range of Acer campestre does not extend north of about 54.3°N in Britain, this map is more accurate. Further north, only planted trees occur. Interestingly, in the last ten years or so, cultivated trees where I am at around 55°N have started to regenerate naturally, which they didn't do before. An example of the real effects of global warming.
Getting proper distribution data was always hard for us, being dependent on free-to-access data and lacking any access to professional GIS software. We mostly relied on the EUFORGEN maps and those in the Den Virtuella Floran (which is currently offline and may be gone forever), and Browicz and colleagues works for the Orient. Since you mentioned the climate shift: the widespread extratropical trees like field maples often are in good agreements with Wladimir Köppen's climate zones (him being as much of a geobotanist than a climatologist). Here's a screenshot of western Eurasia, where we have A. campestre and A. orthocampestre. Note the Cfa/Cfb (fully humid warm to hot summers) patches stretching east along the Black Sea into the Caucasus and Iran, which is also the band the field maples follow. Also quite interesting is that towards the north, the natural distribution of the field maples does not encompass the totality of the Cfb but you do find them planted in e.g. Stockholm and surroundings, too. And while they extend into the cool-Mediterranean climate (Csb, summer-dry), they largely avoid the full-Meditteranean one (Csa). One can also see that the eastern species, the A. orthocampestre, pretty much fills the same general climatic niche than its western counterparts (A. campestre s.str.) Otherwise they only extend into the continental snow (Dfb) climates of Belarus and N. Ukraine and W. Russia. Their Japanese counterpart (A. miyabei, which has a much more relict distribution) seems to be chiefly Dfb (mountains of N./E. Honshu into Hokkaido). This overlay, an open access/data kmz-file for GoogleEarth available for download at the given source, is based on the climate station data of the last quarter of the 20th century. I found it very handy for our research, but it's also very nice from a public/general interest point of view. The people in Vienna that put this together (they are sitting at the Vetenary University) also provide maps for several warming-up scenarios for 2000–2100. Which may be interesting also for horticultural aspects as a general guideline what to expect or why we suddenly find new trees around us (for instance, the Cfa in SW. France is already tilting into Csa, and species like Quercus ilex, the Mediterranean oak expand naturally in this area; 2050 onwards, we may have Cs climates in the Loire Valley but also along the Channel)
Thanks! What Köppen's map doesn't show, is the more extreme oceanic climate of northern and western Britain, where summer temperatures are limited; this - inadequate degree-days of heat for seed maturation - I suspect is the major limiting factor for the northern boundary of Acer campestre, but it is all within the limits of Cfb (that Cfb includes the very different climates of western Ireland, and eastern Poland, shows it is too coarse!!). What would be interesting would be to plot the northern limit of the native range relative to the 16° July-August isotherm; southern and central England are south of this line, but Scotland and northern England are north of it. As for Quercus ilex, that is already an invasive species in southern England . . .
That makes sense. Climate zones are always too coarse because they are generalisations. The oceanic-continental aspect is better captured by Trevartha's modification, but there's no easy-to-access map for his Do (western oceanic) vs. Dc (eastern continental) climates, which more or less replace Köppen's Cfb (for most species, we looked at, the Cf subcategories are just broad enough, though, as we can trace them in the plant associations back into the past). Plotting specific (bio)climatic parameters with gridded data at hand has become very easy. But science is desperately short on hands to collect and process controlled distribution data. The only ready-to-access resource, we do have is GBIF. It's not prefect but, with some cleaning (note the occurrence in Ulster and Stockholm), relatively ok for general associations and test primary limiting factors. The paucity of data points along the Turkish Black Sea coast is a general documentation bias in the collections that have been digitalised so far: the ordinary trees are often underrepresented in their main areas, being not interesting enough to warrent collection. Here's how it looks with "Observation" and "Human observation" added. Note the entire coverage of the British islands, including the chilly west. There's a question, we often pondered when looking into climatic niches of the tree species and genera we studied: should one distinguish between natural and invasive areas at all? Also regarding the question of invasions and adaptability to the changing climate, we should always look at the maximum potential niche, not only the natural-realised one. All very interesting, indeed. But still, working hours involved no-one would be paid for in the science business. We never had the funding to pay those extra hands.
Know what you mean! Far too often, data is flawed because of poor quality control; that's easily seen on sites like iNaturalist by the distribution of records of obvious planted trees not ticked as 'planted' and thus default-listed as 'wild'. So often, that information is available, but not asked - person A enters an occurrence, but didn't talk to person B who could add "I remember the Council planting that 35 years ago".
