I had always thought that this tree that grew sponbtaneously in my garden was an Acer campestre (Field maple), there are many around where I live.
So I just put it in a hedge and let it grow, trimming it each year.
But I'm having doubts now: the leaves look a bit bigger than the ones I can see around (about 7-8 cm for the largest ones) and shinier. Their shape too is not exactly the same as the othrers : they more rounded, less "cut" (can't find the right term in English, indented?...)
The bark of some younger branches are also of a sort of corky texture (as in picture 3).
When cut, the stems or the young shoots yield a white, tastless sap.
Unfortunately, it hasn't produced samaras yet.
So, do you think it's a natural variation as can happen anywhere, a hybrid, or another species?
For a while, I thought it might be a cross between Acer opalus and another subspecies of Acer, because of the shape of the leaves, but this region is not its natural habitat, and I've never seen one in miles around, whether in a botanical garden, a private garden or a garden center.
Acer opalus is quite rare in France, so it's unlikely to be a hybrid from that source. Maybe a cross with
the much more common monspessulanum. Or perhaps just an extreme example of polymorphism.
I think it is a maple, anyway. Any flowers at all? The corky bark is actually reasonably typical of
campestre, especially in very sunny locations.
An interesting and attractive plant, under any circumstances.
I'd say it is Field Maple, just an unusual leaf shape variant. Similar abnormal leaf shape variants have been described in other maples, such as Acer platanoides 'Tharand' or Acer platanoides 'Cucullatum'. Maybe you might want to think about describing this one as a new cultivar.
Whatever it is, it's definitely quite different from other spontaneous seedlings in my garden. I already mentioned the "winged A. campestre" I have, the mother-tree also has this suberous bark on some of its younger shoots.
I took some root-cuttings (a very easy way to propagate some of the non-grafted species), and they look alike. Compare with another seedling found in the garden:
How about a monspessulanum X campestre? The former is pretty common, and a cross could make something like yours.
It seems most specialists now exclude hybridation between monspessulanum and campestre, at least from what I can read on the net.
It could be an interesting explanation though, but:
1/ the leaves on a mature specimen are larger than the leaves of the supposed parents. Not impossible, but unlikely, isn't it?
2/ I haven't ever seen an A. monspessulanum in my area. even my "bonsai friends" don't have any. But since I've had one in a hedge for nearly 20 years (a seedling from Brive-la-Gaillarde) and a few potted ones (from Ardèche), there might be a few hidden in a tree-lover somewhere around ;)
Mine have never flowered so far, or perhaps there were too few flowers for me to notice, but I doubt it.
I'll try to see if anyone at the INRA nest to where I live is interested in examining it - for free, of course! ;°) I've just looked for their website, and I saw they have a section in which they do research on "Exploration de la variabilité naturelle des espèces" (do I need to translate?).
So I'll contact Luc PAQUES and let you know when I get a reply.