The Caucasian Wingnut of the TU Schaugärten

This is the third Caucasian wingnut on this list, which says more about nineteenth-century German gardeners than it does about the Caucasus. Berlin protected it on 2 March 1993 as natural monument 6-40/B and recorded almost nothing else: a species, a place, no age, no girth. The place is the point. From 1903 until 1966 these grounds in Dahlem were the Koenigliche Gaertnerlehranstalt, the Prussian state's teaching institute for gardeners, where the planting was the syllabus. Species came here to be studied, which is how a walnut relative from the forests between the Black Sea and the Caspian ended up behind what is now a computing institute. The school closed, the garden went quiet for decades, and TU Berlin restored it between 2012 and 2014 as a teaching garden again. Late summer is when a wingnut declares itself. The seed chains hang out of the crown in strings up to forty centimetres long, each nut carrying two papery wings, and nothing else in this garden does anything remotely like it. The leaves are long and pinnate, closer to an ash than to the walnut it is actually related to. Nobody has dated this one and nobody has published a girth for it. If you have put a tape round the trunk, tell us.