tribasic acid: an acid containing three replaceable hydrogen atoms per molecule
acid: any of various water-soluble compounds having a sour taste and capable of turning litmus red and reacting with a base to form a salt
bryopsida: true mosses: bryophytes having leafy rather than thalloid gametophytes: comprises orders Andreaeales; Bryales; Dicranales; Eubryales; Sphagnales