Publication: Fl. Bor.-Amer. 1: 332, plate 115. 1834.
selected vouchers: WTU
Notes: FNA20: "Plants of Senecio triangularis with narrow, subentire leaves that taper to the petioles are occasionally encountered in acid bogs in Oregon and Washington and less frequently elsewhere. They are regarded as edaphic variants; they have been recognized as var. angustifolius."
Var. angustifolius of southern OR & CA is distinct (Chambers and Sundberg, 2000).