The Box-leaved Milkwort is a shrubby mountain plant with a woody branching stem and leathery evergreen leaves, which resemble those of the common box but are somewhat thicker. The flowers occur singly or in pairs in the axils of the upper leaves. They consist of a boat-shaped corolla of a pale yellow colour, which becomes darker towards the tip, and two wing-like appendages, which look like petals but are really sepals. These are usually white but are sometimes purple red. It is stated that their colour is determined by the soil on which the plant grows and is white or pure slate; on calcareous, slate coloured.

The Box-leaved Milkwort is widely distributed in Switzerland, Germany, and Austria, between 1500 and 7000 feet, and grows on wooded hills and in dry rocky places, where it is often extremely abundant. It flowers from May till the end of August. The plant is quite distinctive and will be readily recognised. Although belonging to the Milkwort tribe it is quite different from all other species, which have red, white or blue, never yellow, flowers and deciduous, not evergreen, leaves.

The Common Milkwort (Polygala vulgaris) of our English downs and heaths is also found in the Alps. It is a small herbaceous plant with a slender stem, perhaps three or four inches long, which is thickly covered with leaves, and terminates in a cluster of pink, blue, or white flowers. Polygala calcarea, a nearly-related species found only in limestone districts, has sky-blue flowers and leaves for the most part clustered in the form of a rosette at the base of the stem.