Probable Base Number for Genus x = 10
S. corumbensis n= 10 ref Robinson et al. 1989
S. oblongifolius 2n= 40 ref Grant 1953 (as Eupatorium oblongifolium)
References
Grant, W. F. 1953. A cytotaxonomic study in the genus Eupatorium. American Journal of Botany 40: 729-742.
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.
Turner, B. L. and W. H. Lewis. 1965. Chromosome numbers in the Compositae. IX. African Species.
Journal of South African Botany 31: 207-217.