The chromosome number of the genus Plagiochilion S. Hatt. (Plagiochilaceae, Hepaticae), n=9, is reported for the first time, based on Chinese material of P. mayebarae S. Hatt. and P. oppositum (Reinw. et al.) S. Hatt. Oil bodies of Plagiochilion oppositum are newly described and illustrated. Oil bodies of cultured material of P. mayebarae contain smaller granules sometimes difficultly recognized, and are slightly different from those from the wild.