Lichens

The distinguished Spanish lichenologist the Revd Father Longinos Navas lists and describes, in his Sinopsis de las Liquenes de las Islas de Madera, 203 species of these curious cellular plants, which, as is well known, consist of an association of an alga with a fungus. The fungus takes carbohydrates from the alga; the alga receives from the fungus protection against drying out, together with a certain quantity of nitrogenous substances. This association is called symbiosis.

Among the Madeiran lichens we may mention the following: Stiacta damaecornis, Pseudocyphellaria aurata, Lobaria pulmonaria, Xanthoria parietina, Usnea florida, Nemaria fuciformis, N. rocella, N. fucoides, Cenomyce pyxidata and various Lecanora, Parmelia, Lecidia, etc. The three species of the genus Nemaria that we have, known as urzelas, were formerly much used to extract a red-violet substance, obtained by fermenting the plants with lime and urine. Lichens are found on tree bark, on rocks and walls, on the ground, etc. See August von Krempelhuber, Stein, Stizenberger, Steiner, Navas.