Probable Base Number for Genus x = 10
S. cuneatus n= 10 ref Coleman 1968
S. decussatus n= 10 ref Robinson et al. 1989
References
Coleman, J. R. 1968. Chromosome numbers in some Brazilian Compositae. Rhodora 70: 228-240.
Robinson, H., A. M. Powell, G. D. Carr, R. M. King, and J. F. Weedin. 1989. Chromosome numbers
in Compositae, XVI: Eupatorieae II. Annals of the Missouri Botanical Garden 76: 1004-1011.