Abstract: The present paper deals with the classification and distriburion of the genus lsometrum Craib (gesmeriacece_____Cyrtandroion) and its rela-tionship with the genus Ancylostemon.The genus under discussion is endemic to China,consisting of ll species (incl.4 new species,one new combination and 2 new varieties)which are grouped into two sections.lts area is rather small,confined to northwestern to eastern Sichuan, the Qinling Range,Daba Range and the mountainous region of western Hubei,with the concentration in northwestern Sichuan. Most species grow on shady and moist rocks and cliffs at the altitude of 500--2000 m,but one or two species occur at the altitude of 2200-2800 m,sometimes even up to 3900 m alt.

Key words: lsometrnm, 1.sichuanicum, 1.pinnatilobatum, Distribution