For Xanthium
Cronquist, A. 1980. Asteraceae, Volume I, Vascular flora of the Southeastern United States. University of North Carolina Press, Chapel Hill, N.C.
Fernald, M.L. 1946. Contributions from the Gray Herbarium of Harvard University -- No. CLX. Technical studies on North American plants. Rhodora 48: 66-81.
Löve, D., and P. Dansereau. 1959. Biosystematic studies on Xanthium: taxonomic appraisal and ecological status. Can. J. Bot. 37: 173-208.
Millspaugh, C.F., and E.E. Sherff. 1919. Revision of the North American species of Xanthium. Field Mus. Nat. Hist. Bot. 4: 9-49.
Strother, J.L. 2006ee. Xanthium. In Flora of North America Editorial Committee. 2006b. Flora of North America north of Mexico. Volume 20, Magnoliophyta: Asteridae, part 6: Asteraceae, part 2. Oxford Univ. Press, New York, NY. 666 pp.
Tomasello, S. 2018. How many names for a beloved genus? -- Coalescent-based species delimitation in Xanthium L. (Ambrosiinae, Asteraceae). Molec. Phyl. & Evol. 127: 135-145.
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