抄録
Marchantia polymorpha L. subsp. polymorpha (=M. polymorpha var. aquatica Nees) has been found in Ozegahara Moor (Niigata Prefecture, Central Honshu). It is the first Japanese collection since the early 1950s. During a field survey in Ozegahara Moor we found it in a wetland (36°56'43"N, 139°14'34"E, 1400 m elev.) located to the east of Toudengoya Hut. This place has heavy snowfall in all months except for July to October and is dominated by Phragmites australis (Cav.) Trin. ex Steud., where M. polymorpha subsp. polymorpha shows turf-forming habit with erect thalli and mat-forming habit with prostrate thalli. Although several plants with prostrate thalli occasionally bear gemma cups and become broader (to 10 mm) with wider branching angles (40-45°) than typical plants with erect thalli, the presence of black midline of thallus and the entire to crenulate ventral scale appendages are stable among populations.
