The wingnut in the Belfast Botanic Gardens is in the process of re-growing from a stump and is not flowering at present. It may be the Caucasian wingnut, Pterocarya fraxinifolia or the hybrid wing nut, Pterocarya x rehderiana. When it flowers again this will be resolved!
The wing nuts are very vigorous trees, mostly from China with one species from Japan and one from the south of the Caspian Sea. The leaves are compound like those of the ash (Fraxinus) and the walnut (Juglans) the latter being in the same family as the wingnut. A feature of the wingnuts, shared with the walnuts, is that the pith in the young stems is segmented as shown in the photo below. They are prolific sucker producers and a single tree can quickly spread to a clump many metres across as the splendid example near the lake in Rowallane Garden shows. The suckers can be controlled if the trees are grown in grass which is kept mown as can be seen in Edinburgh Botanic Garden.
NOTE 2019: The Pteriocarya in Belfast is now more than twice the size it was in 2010 and is flowering prolifically. There is still some uncertainty about the identification, but it appears more like P. fraxinifolia
|Wingnut in Belfast Botanic Gardens||Flowering wingnut in Rowallane Garden|
|Flower of hybrid wingnut (Edinburgh Botanic Gardens)||Segmented pith inside young stem of Wingnut tree|
Photos taken in Belfast Botanic Gardens, Rowallane garden and Edinburgh Botanic Garden in 2010. Copyright: Friends of Belfast Botanic Gardens.
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