Polygala calcarea, the chalk milkwort, is a species of flowering plant in the family Polygalaceae, native to western Europe.

It is a delicate mat-forming evergreen perennial growing to 5 cm (2 in) tall by 20 cm (8 in) broad, with spikes of small, vivid deep blue flowers in spring, and leathery, oval leaves.

[1] The specific epithet calcarea means "growing in lime", though this plant will grow in a range of soils.

[2] It prefers sharply drained conditions, and is suitable for cultivation in an alpine garden.

The cultivar 'Lillet' has gained the Royal Horticultural Society's Award of Garden Merit.