Hi André, Looking at your photo, I think this is Acer campestre - it does not look like other photos of A. hyrcanum I have looked at, which show broader-based lobes with slightly recessed veins, less glossy-smooth looking. To check, break a leaf stem and see if the sap is milky (A. campestre) or not
I can't check because I took these pictures in an arboretum near Orleans, France. But it's a very serious one and I think they know what they're talking about ;-)
Maples for Gardens shows a plant with less decisive lobing, but also says the leaves of this species are "very variable". Likewise, North American Landscape Trees says "Leaves...resembling those of A. campestre and A. Miyabei."
It's pretty easy for any institution to make a mistake (speaking from experience), particularly when dealing with a group of plants that has a lot of morphological variability within a species compounded by the fact that it may have variable leaves between juvenile and adult stages (e.g., it may have been identified as such when young, and not verified since with a critical eye). It'd be worthwhile to double-check the plant when the opportunity next presents itself, just in case.
Reviving this old thread with a proper picture of A. hyrcanum leaves. I agree that the OPs picture is likely campestre. The attached is a picture of leaves from an A. hyrcanum cloned from a collection by de Jong in Turkey. Sometimes appears as 'Alma Mater' after the place of origin, though I haven't found where this is in Turkey. And indeed mistakes show up in institutions, collections, arboreta as Daniel says. In fact it's rare to find a collection without any!
Which one? "Arboretum National des Barres" or "Arboretum des Grandes Bruyères"? Still haven't visited either of them, but I will, I will...
