Collomia linearis
USDA-NRCS PLANTS Database / Britton, N.L., and A. Brown. 1913. An illustrated flora of the northern United States, Canada and the British Possessions. Vol. 3: 64. - Foto visualizzata 34 volte

Polemonium caeruleum
Credit: Photo by Pierfranco Arrigoni - Valmadrera (LC) - Foto visualizzata 17 volte

Polemonium coeruleum
C. Hoffmann - Botanischer Bilder-Atlas (1884) - This image is in the public domain because its copyright has expired. - Foto visualizzata 15 volte