Today’s “Plant of the Day” is a real beauty: Centraurea montana L. from the Asteraceae (or Compositae) family. In German, the species is known as “Berg-Flockenblume”. In English, the species has different names like “mountain cornflower”, “Bachelor's button” or “mountain knapweed”.
Please note: According to current researches, the species belongs to the new genus Cyanus (along with Centaurea cyanus L. and Centaurea triumfetti (Gugler) Dorstal). So, its new name is Cyanus montanus. However, in most books the species still has its old name, so I also will use it in this post.
C. montana - habitus
C. montana is a perennial plant, which can reach heights between 30 and 60 centimeters (12 to 26.3 inches). The whole plant is covered with small, felty hairs. The leaves are lanceolate to egg-shaped and have a smooth margin, which isn't serrated or deeply lobed. However, there is a white line along the whole margin.
C. montana - foliage
The leaf-bases are decurrent on the stalk. Thus there is no petiole and the leaves sitting directly at the stalk. Leaves have a dark-green color. In addition, young plants are dense covered by the hairs, so they shimmer silvery. However, foliage leaves get bald with age and are more green than silvery.
C. montana - invulucrum (note the black fringes of the bracts)
A distinctive feature of C. montana are the bracts, which are covering the inflorescence. If you remember to my Article about the Asteraceae, you know that this hull of bracts is called Invulucrum. The small bracts are triangular and overlap each other like tiles. They have small fringes at the edge, which have a black color.
C. montana - inflorescence
During late spring, the Invulucrum opens and releases the beautiful inflorescence. Like all Asteraceae, the inflorescence of C. montana heads, which consists of many single flowers. These heads are between 3 and 5 centimeters (1.3 to 5 inches) in diameter.
C. montana - inflorescence
As member of the Carduoideae, the heads of C. montana consists only of disc flowers but there are two kinds of them. The disc flowers in the center have a violet color and are smaller than the peripheral disc flowers, which have a deeper purple color. These flowers are also elongated and frayed and fleeced at the top. Flowering time is between May and August.
C. montana - stalk with hairs
In some cases, C. montana is confused with Centaurea triumfetti,a closely related species. The best way to distinguish these two species is to look at the fringes of the bracts. The fringes of C. triumfetti are much longer and more brown than black. In addition, the leaves of C. triumfetti are more hairy, because they don't getting bald. However, a clear distinction isn't always possible. Especially in gardens, there are many hybrids between these two species.
2) Ecology & Distribution
Originally, C. montana is endemic to the mountains of Southern and Middle Europe. As the name “montana” suggests, it's a plant of mountainous regions and grows on rocky slopes, in ravine forests and mountain forests and on high meadows, where it prefers nutrient-rich places.
However, C. montana is also an ornamental plant and popular with Gardeners, because of its flowers and small claims towards its growing places. It can grow in light and semi-shadow and as a mountain plant, it has no differences with hard, rocky soil. This circumstances have helped, that the plant has also become native outside of its original areal. For example, C. montana can be found in England, Scandinavia and even in North America.