An erect cylindrical thallus terminated by the fruit is termed a podetium, as in Cladonia (fig.
M, Medullary layer of the C, Cladonia novae Angliae, B, Portion of a very thin Delise; sterigmata section from the base with spermatia from of the spermogonium.
Lecanora subfusca, Cladonia pyxidata); and others, not strictly cosmopolitan, have been observed in regions widely apart.
The chief of those employed for one or other, and in some cases for several, of these purposes were Cladonia pyxidata, Usnea barbata, Ramalina farinacea, Evernia prunastri, Cetraria islandica, Sticta pulmonaria, Parmelia saxatilis, Xanthoria parietina and Pertusaria amara.
In arctic regions lichens form by far the largest portion of the vegetation, occurring everywhere on the ground and on rocks, and fruiting freely; while terrestrial species of Cladonia and Stereocaulon are seen in the greatest luxuriance and abundance spreading over extensive tracts almost to the entire exclusion of other vegetation.
Species of Usnea and Ramalina, also Evernia furfuracea and Cladonia rangiferina, were used in the art of perfumery.
Schimper distinguishes moss tundra, Pot ytrichum tundra, and lichen tundra; and the lichen tundra is subdivided into Cladonia tundra, Platysma tundra, and Alectoria heath.
The podetia of some species of Cladonia possess no cortical layer at all.
In connexion with their use as food we may observe that of recent years in Scandinavia and Russia an alcoholic spirit has been distilled from Cladonia rangiferina and extensively consumed, especially in seasons when potatoes were scarce and dear.
E, Pleurococcus Sp. (Cystococcus) from the thallus of Cladonia furcata.