Convolvulus sepium var. americanus Sims

POWO follows these authorities in synonymising this name:

• Austin, D. F. & M. Costea in Zuloaga, F. O., O. Morrone, & M. J. Belgrano (2008). Convolvulaceae. Catálogo de las plantas vascualres del Cono Sur 2: 1936-1966. Missouri Bot. Garden. [Cited as Calystegia sepium subsp. americana.]
• Fernald & Rollins in Fernald, M.L. with R. C. Rollins (1950). Gray's Manual of Botany, 8th edition: 1177-1185. Dioscorides Press. [Cited as Convolvulus sepium (typical).]
• Govaerts, R. (1999). World Checklist of Seed Plants 3(1, 2a & 2b): 1-1532. MIM, Deurne. [Cited as Calystegia sepium subsp. americanus.]
• Kartesz, J.T. in Kartesz, J.T. (1994). Convolvulaceae. A synonymized checklist of the vascular flora of the United States, Canada, and Greenland: 217-221. Timber Press. [Cited as Calystegia sepium subsp. americana.]
• Manitz, H. (1983). Zur Nomenklatur einiger Convolvulaceae und Cuscutaceae. I. Feddes Repertorium 94: 173-182. [Cited as Calystegia sepium subsp. americana.]

This name was accepted following an alternative taxonomy by these authorities:

• Gray, A. in Gray, A. (1878). Convolvulaceae. Synoptical Flora of North America, edit. 1 2(2): 207-224, 394. [Cited as Convolvulus sepium subsp americanus.]
• Gray, A. in Gray, A. (1886). CNV, supplement, in Syn. Fl. N. Amer. Ed. 2. Synoptical Flora of North America, edit. 1: 433-436. [Cited as Calystegia sepium var. americana.]