Euphorbia corollata

A white flowered Euphorbia - who knew? In this case fairly normal looking bushy spurge plants produce increasingly wide branching sprays of small pure white flowers in summer – more like a Gypsophila or a Linum perhaps. 

This species originates in Eastern North America so should be completely cold hardy. So far it has been easy and vigorous in a sunny spot. Not invasive.
£8