Uisinn (Fraxinus excelsior)

Uisinn is the Gaelic name for the Ash tree - (the fourth commonest tree in Britain apparently - although I am not sure who has checked and how...).  These are the seeds, or 'keys' of an Uisinn seen growing in Bridgend Woods.  Every Primary school child is told how clever Mother Nature has been to devise these clever winged seeds so that the tree's progeny can be spread far and wide on the wind.  I was never impressed by this argument as a boy - anyone who has ever tried to make an ash key fly on the breeze will soon deduce that they are aerodynamically hopeless. 
Ash keys however, are slightly better fliers than the keys of the Sycamore, which although they make brilliant spinning aerofoils when you break them from their siblings, almost always fall off the tree as conjoined pairs - which have the aerodynamic qualities of your average brick.  Strange thing, nature...
Carl