The Collaborative International Dictionary of English v.0.48:

Lungwort \Lung"wort`\, n. (Bot.)
   (a) An herb of the genus Pulmonaria (Pulmonaria
       officinalis), of Europe; -- so called because the
       spotted appearance of the leaves resembles that of a
       diseased lung.
   (b) Any plant of the genus Mertensia (esp. Mertensia
       Virginica and Mertensia Sibirica), plants nearly
       related to Pulmonaria. The American lungwort is
       Mertensia Virginica, Virginia cowslip. --Gray.
       [1913 Webster]

   Cow's lungwort mullein.

   Sea lungwort, Mertensia maritima, found on the seacoast
      of Northern Europe and America.

   Tree lungwort, a lichen (Sticta pulmonacea) growing on
      trees and rocks. The thallus is lacunose, and in
      appearance somewhat resembles the lungs, for diseases of
      which it was once thought a remedy.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Cow's lungwort \Cow's" lung"wort`\ (kouz" l?ng"w?rt`).
   Mullein.
   [1913 Webster]