18. Didymodon tophaceus (Brid.) Lisa 灰土对齿藓 hui-tu dui-chi xian
Elenc. Musch. 31. 1837. Barbula tophacea (Brid.) Mitt., J. Proc. Linn. Soc., Bot., Suppl. 1: 135. 1859. Trichostomum tophaceum Brid., Muscol. Recent. Suppl. 4: 84. 1819 [1818]. Type. Europe.
Plants medium-sized to large, 30–60 mm high, green to brownish green, in dense tufts. Stems erect, often branched. Leaves appressed, but usually contorted-curved when dry, obliquely spreading when moist, oblong-ovate, gradually narrowed toward a round apex; margins entire, revolute; costa stout, ending just below the apex; upper leaf cells rounded triangular to pentagonal, thick-walled, sparsely unipapillose; basal cells slightly longer, short-rectangular. Setae slender, reddish brown; capsules erect, cylindrical; peristome teeth short, straight, divided deeply to the base; opercula conic-rostrate, with a short beak.