This section is from the book "British Wild Flowers - In Their Natural Haunts Vol2-4", by A. R. Horwood. Also available from Amazon: A British Wild Flowers In Their Natural Haunts.
Not being native in this country, Lungwort is not found in any early deposits. It is a member of the Northern Temperate Flora of Europe. It is not an indigenous plant, and is regarded by Watson as an introduction in the thirty odd counties in which it occurs in S. Scotland and England.
Everywhere it is rare and merely naturalized, having escaped from cultivation in the garden, and it is usually found in copses and similar woodland habitats close to houses, by the owners of which, in the first instance, it has been dispersed by planting with other plants, such as Periwinkle, Spurge Laurel, and some others equally under suspicion.
The name Lungwort, translated from the first Latin name, refers to a character of the leaves, which have a spotted appearance. It is an erect, hairy, slender-stemmed plant with alternate leaves, the radical-leaves being egg-shaped or heart-shaped, rough, the stem-leaves stalk-less and egg-shaped. The leaves are spotted with pale-green patches about a quarter of an inch across.
The flowers are pale purple or pink, and of two forms, long- and short-styled, the short-styled form having larger flowers. The flower-stalks are simple and the flowers in terminal forked cymes. The calyx is as long as the straight tube of the corolla. The corolla, first pink (like others), turns blue later, hence the flowers present a variegated appearance.
The stem is 1 foot high. The Lungwort flowers in May and June.