Publication: Manual of Botany of the Northern United States (ed. 2). 430. 1856.
selected vouchers: WTU
Notes: We follow Abrams, FNA, and Kew Index, treating the author as Engelm. in A. Gray, and not Engelm. ex A. Gray, as in KZ99; perhaps not distinct from the European S. erectum L.
H. Hara published this combination in 1976; Cook & Nichols combination in 1987 is superfluous