Using transmission electron microscopy, histochemistry, and analytical techniques, lipids are shown to constitute the most important cytoplasmic fraction in ten species of Grimmia. Major compounds common to these species are identified as β-sitosterol, linoleic acid, and α-amyrin acetate. The triterpenoid, α-amyrin, has rarely been reported in mosses, and its possible chemotaxonomic value is pointed out.