4. Zinc, Copper.—Soils which contain zinc, although of rather limited extent, claim a few strictly characteristic elementary species such as Viola calaminaria, which is related to Viola lutea, and several elementary species of Thlaspi. According to Douin, a few liverworts are favorable to heavy metals, especially copper, while of central European species only Mielichhoferia nitida is stated to be copper favoring. In the Andes, however, according to Herzog, numerous species of Mielichhoferia are said to exist as copper favorites. (Braun-Blanquet 1932:191)
BRAUN-BLANQUET, Josias. 1932. Plant sociology: the study of plant communities. (Trans.: George D. Fuller; Henry S. Conard) New York: McGraw-Hill Book Company.