Spiny Clotbur, Spiny Cocklebur, Spiny Cockleburr: Xanthium spinosum (Synonyms: Acanthoxanthium spinosum, Xanthium ambrosioides, Xanthium spinosum var. inerme) - Stems with 2- or 3-branched spines at the nodes.
Canada Cocklebur, Common Cocklebur, Rough Cocklebur: Xanthium strumarium (Synonyms: Xanthium strumarium var. canadense , Xanthium strumarium var. glabratum, Xanthium strumarium var. oviforme, Xanthium strumarium var. pensylvanicum, Xanthium strumarium var. strumarium) - Plants spineless.