A New Species and a New Variety of Porella (Porellaceae, Marchantiophyta) from China KARYOTYPE STUDIES OF FOUR SPECIES OF PORELLACEAE FROM CHINA A New Species and a New Variety of Porella (Porellaceae, Marchantiophyta) from China Three New Species of Porella from Mountain Hengduan, China Chemical constituents of volatile oil from Porella paraphyllia