Centaurea uniflora ssp uniflora

Perennial of the Asteraceae family, Centaurea uniflora is a species of the Alps, present in the Alpine ranges of France, Italy, and Switzerland. It occupies high-altitude grasslands, stabilized scree, rocky slopes, and poor meadows on calcareous or siliceous substrate, generally between 1,500 and 2,800 meters. It is a strictly mountainous species, faithful to the subalpine and alpine levels.

It stands with simple, slightly branched stems, 15 to 40 cm tall, each bearing a single terminal capitulum, as its epithet indicates. This uniflorous trait, rare in the genus, gives it a slender and sober silhouette, very different from the bushy centaureas with multiple blooms. The basal leaves are long-petioled, oblong to lanceolate, slightly tomentose and grayish, while the cauline leaves, sessile and decurrent, are narrower.

The single capitulum is of a beautiful size, with tubular flowers of a deep pink-purple to violet, surrounded by slightly enlarged peripheral flowers. The involucre is characteristic: the scales bear pectinate appendages with fringes of stiff, dark-brownish cilia, forming a dark and velvety ornamental collar that frames the flowers.

In its natural habitat, its flowering extends from July to August. In cultivation, it requires well-drained, mineral, and low-fertility soil, in a sunny exposure; it is suitable for Alpine rock gardens and mountain gardens, but remains demanding outside its natural level.