13 



Sticta pulmonaria. Lung Lichen 



Also called Lobaria pulmonaria. Found occasionally through- 

 out the New York area on tree-bark, over moss at the bases of 

 trees, or on rocks. It forms rather regular, open rosettes up to 

 25 cm. across, with branches 1 cm. or more wide, ending in 

 angularly tipped lobes usually about 5 mm. wide. The tips are 

 commonly lifted from the foothold as much as 1 cm. Color 

 varies from pale greenish gray to brownish or even blackish when 

 dry, olive-green when moist. The surface is pitted as much as 

 4 mm. deep, with rounded ribs forming a network between the 

 pits, while the lifted margins and sometimes the ribs may be 

 studded with dusty, gray soredia, with prongs or coral like growths, 

 or with miniature lobes. The under surface is a reverse of the 

 upper, because the substance is thin, and like paper impressed with 

 a seal. The pits of the upper surface become lumps below, the 

 ribs become grooves. The color beneath is buff near the margins, 

 more or less covered with a brownish down, becoming dark brown 

 toward the center. But the humps tend to be bare of down, and 

 show pale buff in contrast to the brownish down of the grooves. 

 The algal cells are not in chains. 



Fruits, not common, are disk- or saucer-shape, reddish brown, 

 up to 4 mm. in diameter, close to the margins of the upper sur- 

 face. Spores 2-celled or 4-celled, 18 to 33 by 6 to 10 microns, color- 

 less when mature. 



Sticta pulmonaria is a striking lichen, unique, but suggesting 

 Cetraria, just as 5". amplissima suggests Parmelia. It approaches 

 Cetraria lacunosa (Group 4), but is easily distinguished by the 

 downy under surface, larger size, and comparatively slight lifting 

 of the tips. 5'. pulmonaria is the most deeply pitted of our lichens. 

 The pitting in Parmelia saxatilis (Group 6) is much shallower, 

 and the under surface wholly black. Other pitted species of Sticta 

 from which S. pulmonaria must be distinguished are 6". scrobicu- 

 lata, S. sylvatica and 5". anthraspis, all northern forms, and all 

 with the under surface distinctly speckled. They are besides less 

 narrowly lobed, and sometimes hardly branched at all, suggesting 

 the Rock Tripes (Group 12). It is worth noting that the pitted 

 structure is exactly the reverse of the blistered pattern in Umbili- 

 caria pustulata and U. pennsylvanica (Group 12). 



