2. Hydrogonium arcuatum (Griff.) Wijk & Marg. 砂地石灰藓 sha-di shi-hui xian
Taxon 7: 289. 1958. Barbula arcuata Griff., Calcutta J. Nat. Hist. 2: 491. 1842. Type. India: Assam.
Hydrogonium comosum (Dozy & Molk.) Hilp., Beih. Bot. Centralbl. 50(2): 622. 1933. Barbula comosa Dozy & Molk., Ann. Sci. Nat., Bot., sér. 3, 2: 299. 1844.
Plants stiff, in dense tufts. Stems erect, simple, rarely branched, radiculose at the base. Leaves erectopatent, ovate- or triangular-lanceolate, gradually acuminate at the apex; margins entire, plane or weakly revolute; costa stout, ending just below the apex; upper leaf cells quadrate to pentagonal, orderly arranged, thin-walled, smooth; basal cells irregularly rectangular, thin-walled, smooth, hyaline. Sporophytes not seen.