Ostraya carpinifolia. It was dancing in the wind at Cambridge Botanic:

Shaking hop dangly earrings in the sunny breeze.

My visit was a quick, lopping one but round a few corners it was a surprise to see the dreaded Fallopia sachalinensis, AKA Japanese Knotweed romping delightedly under a massy fir.  In the same area Ricinis Communis, the caster oil plant, with its poisonous association with umbrella tips, was lolling in a bed.  Dead lovely.  No doubt I was in the toxic zone.