Common Cocklebur resembles Arctium minus (Common Burdock) somewhat, but it has separate male and female flowers that are brownish white and green, respectively, while the latter species has perfect flowers with bright pink corollas. Because Common Cocklebur is a highly variable plant, different varieties have been identified (or even regarded as separate species in the past). The other variety of Common Cocklebur in Illinois, var. glabratum, has bur-like bracts that are nearly glabrous and they tend to be more oval-shaped and less broad than the bracts of var. canadense. Otherwise, they are very similar to each other. Another species that is adventive from the southwest, Xanthium spinosum (Spiny Cocklebur), is rarely encountered in Illinois. It has more narrow lanceolate leaves, and there is a tripartite spine at the base of each leaf.