Saxifraga callosa

Saxifraga callosa, the limestone saxifrage, is a species of flowering plant in the family Saxifragaceae, that is native to maritime alpine habitats in Western Europe (Italy, France and Spain). Growing to tall by broad, it is a clump-forming evergreen perennial with rosettes of narrow grey-green leaves that are coated in lime. The starry, pure white flowers are borne in long panicles in spring.
The Latin specific epithet "callosa" means “thick-skinned, with calluses”.
Lower taxa.
"Saxifraga callosa" is a variable species depending on location, Two subspecies and at least two varieties are recognised:- 
Cultivation.
"Saxifraga callosa" is cultivated as an ornamental garden plant. As it requires well-drained alkaline soil in full sun, it is often grown in an alpine house, where specialist conditions can be provided. It has gained the Royal Horticultural Society’s Award of Garden Merit.