Abstract: Marchantia paleacea subsp. diptera is a dominant bryophyte species in Tianhetan karst mountainous wetlands and mainly grows on steep slopes of artificial ditches and artificial ladders with intense human disturbance, and in shady and moist environment. The gemma cups of M. paleacea subsp. diptera are influenced by slope. Our investigation showed that the size distribution of gemma cups of M. paleacea subsp. diptera was concentrated in March. On average, a sample (specimens of a quadrat frame in 0.1 m×0.1 m) contained 22.5 gemma cups, and a gemma cup contained 120 gemmae. The gemma production of each M. paleacea subsp. diptera sample was from 155 to 12020, with an average of 2940 gemmae. The gemma density was from 72567 to 1202040 ind·m^-2, with an average of 480408 ind·m^-2. In August, the size distribution of gemma cups was more uniform, there were on average 30 gemma cups per sample, and a gemma cup contained 148 gemmae. The output of gemmae per sample was from 1152 to 10118, and a sample contained on average 4379 gemmae. The gemma density was from 116160 to 1470750
ind·m^-2, with an average of 687591 ind·m^-2. Therefore, there was more gemma production in August (summer) than in March (spring), indicating that August was more suitable for the formation of gemmae. The production of gemmae might be greatly influenced by the environmental temperature and precipitation in different seasons, and the higher temperature and more precipitation, the more production of gammae was. Furthermore, there was a good correlation among the five biological components such as fresh thallus weight, dry thallus weight, etc. This study provides a basis for gemma vegetative reproduction of Marchantia species and ecological management of Tianhetan karst wetlands.

Key words: relict plant, micro-topographic unit, regeneration type, reproduction mode, ecological species group.