About this variety
Musk mallow is a British native and one of the better-behaved ones. The white form makes a rounded plant under a metre high, with finely divided ferny foliage and a long succession of clean white saucer flowers from June into September.
It is genuinely useful for wildlife, drawing bees and hoverflies steadily rather than in one short burst. Cut it back after the first flush and it will produce a second, smaller one in late summer.
Individual plants are not especially long-lived, three or four years at most, but it seeds itself gently around the place and there is always a replacement coming. It asks for almost nothing beyond reasonable drainage.