Potentilla pensylvanica

A species widely distributed throughout the world, but known in the Alps from just three locations in the Aosta Valley, one of which is in the Cogne Valley. In Europe, it is native only to Spain and, having been introduced by humans, to the Czech Republic and Slovakia. Very rare at all its locations in the Aosta Valley, P. pensylvanica is listed on the IUCN Red List as a species threatened with extinction at national level. It is therefore a strictly protected species.

The plant is found on detrital soils and sunny grasslands at altitudes, for the known sites in the Alps, ranging between 1,000 and 1,600 metres. It has erect stems and the basal leaves are imparipinnate (i.e. feather-shaped with a single leaflet at the apex), composed of 5–7 segments, deeply toothed at the margins. The flowers, arranged in a corymb inflorescence, have a yellow corolla comprising five petals. The entire plant is more or less covered in a fine down, giving it a characteristic grey-green colour.