The basal leaves are green, cordate, more or less elongated and pointed and always with rounded and often sharply defined white or pale green patches. The upper surface of the leaves has tiny bumps and it is quite hairy. The leaves of this host plant are eaten by the caterpillars of the moth Ethmia pusiella. In spring, the plant produces small bunches of flowers. The 5-petal flowers are red or pink at first, later turn to blue-purple during the anthesis, by changing the pH value inside of the petals. As a matter of fact the flowers contain a dye that belongs to the anthocyanins and change the color from red (acidic) to blue (alkaline). Pulmonaria officinalis is diploid and has the chromosome number 2n = 14. Flowering period extends from March through May and the seeds ripen from May to June. Pollination is granted by insects (entomophily) – mainly bees, bumblebees and butterflies – the spread of seeds over ants.