Bryology is …

… the study of mosses and their relatives (<Gk. bryon, “a moss,” or <Gk. bryos, “moss,” in turn <Gk. bryo, “to sprout, to grow, swell or teem with” + -logy, < Gk. –logia, “a speaking, discourse, treatise, doctrine, theory, science.”  (See the CRC World Dictionary of Plant Names, Volume 1: A-C and the Online Etymology Dictionary for details.)  The following sources can give you some further ideas regarding the definition and attributes of bryology: