Karyological studies on the Sino-Himalayan genus, Cremanthodium (Asteraceae : Senecioneae)

Twenty-two populations of seven species of Cremanthodium from high altitude regions of western China were observed karyologically. C. ellisii, C. micr oglossum, C. brunneo-pilosum, C. stenoglossum, C. discoideum and C. lineare all had the same chromosome number of 2n=58 whereas C. humile had 2n=60. A ll chromosome numbers of these species are documented here for the first ti me. The basic number of x=30 is new for this genus. The karyotypes of all s pecies belong to 2A type according to Stebbins' asymmetry classification of karyotypes. Two basic chromosome numbers, x=30 and x=29 in Cremanthodium, correspond exactly to two branching patterns in this genus, sympodial versu s monopodial. The systematic and taxonomic statuses of the sympodial specie s need further study. The karyomorphological data provide no support to the sectional subdivision in Cremanthodium. (C) 2001 The Linnean Society of Lo ndon.