The Effect of pH on the Growth of Protonemata of Tetraplodon mnioides and Funaria hygrometrica

The effect of pH on growth of protonemata of Tetraplodon mnioides (Hedw.) B.S.G. and Funaria hygrometrica Hedw. was studied for 5 weeks at initial pH levels of 3.5, 5.8, 6.4, and 7.8 in two different media. Protonemata of both species increased in dry weight significantly at each suc- ceeding pH. There was a significant difference in growth of protonemata in two media, but there was no significant difference in growth between two species. Also, there was no significant interaction between any of sources of error. pH may be important as a limiting factor in restricting habita~t of Tetraplodon mnioides and Funaria hygrometrica. There is a considerable body of literature dealing with mosses, but a great deal of it is concerned with where mosses are found, not why they are found there. In spite of this, it is opinion of Richards (1932) that the response of bryophytes to edaphic factors is certainly sharper and clearer than that of flowering plants. He suggested that bryophytes are at a great disadvantage in competition with vascular plants and that any factor which limits growth of herbs favors growth of mosses. Supporting this, Shacklette (1961) suggested that exclusive bryophyte communities of Latouche Island, Alaska were not in competition with vascular plants because of mosses