Silver thistle

(Carlina acaulis)

This species is widely distributed in Europe and prefers dry and warm, grazed nutrient-poor grassland on base-rich soil. It is found from the valley floor up to the subalpine level.

Description/characteristics

The plant is perennial and has a tap root up to one metre deep. It is almost stalkless, thus the up to 15 cm long, prickly dentate leaves are arranged around the silvery-white blossom like a rosette. The blooming period spans from July to September.

Special features

In the vernacular, the silver thistle is also called weather thistle, as it is able to predict poor weather: When rain is approaching, the humidity rises. As the plant absorbs more water vapour on the underside of the bract than on the upper side, the bracts bend inwards and form a rain cover over the anthodium with the tubular flowers. The aromatically fragrant rhizome finds many uses in popular medicine. The plant’s receptacle is edible and has thus earned it the additional name of “Hunter’s bread”.

Endangerment/protection

The silver thistle is most commonly found in Austria. In the Pannonikum, the northern Alpine foothills, and in the Bohemian Massif it is, however, endangered and should thus not be picked.

Literature

ADLER, W., OSWALD, K. & FISCHER, R. 2005. Exkursionsflora für Österreich, Liechtenstein und Südtirol.-2nd edition.