5. Hydrogonium gracilentum (Mitt.) P.-C. Chen, Hedwigia. 80:237. 1941; Barbula gracilenta Mitt., J. Proc. Linn. Soc., Bot., Suppl. 1: 35. 1859.
细叶石灰藓
Plants stiff, in dense tufts. Leaves triangular-lanceolate, gradually acuminate; margins entire, revolute in the lower half, serrulate in the upper half; costa slender, percurrent; upper leaf cells quadrate to hexagonal, thin-walled, smooth; basal cells larger, irregularly rectangular. Sporophytes not seen.
Type. Himalaya: T. Thomson 189 (holotype NY).
Chinese specimens examined: HENAN: Xin-yang Co., Ji-gong Shan (Mt.), H.-J. Yu 45 (PE). LIAONING: Feng-cheng Co., C. Gao 1092 (HKAS, IFSBH). SICHUAN: Dao-cheng Co., X.-J. Li 7151 (HKAS); De-rong Co., X.-J. Li 81–2860 (HKAS). XINJIANG: He-jing Co., S. He 951220 (MO). XIZANG: Long-zi Co., Zhun-ba, M. Zang 1174 (HKAS); Mi-lin Co., Xizang Exped. Team 7408 (HKAS); Ya-dong Co., M. Zang 194 (HKAS).
Habitat: on rocks or soil walls in forests; Distribution: China, India, and Pakistan.
Illustrations: Pl. 125, figs. 1–2.
