Xanthium ser. Glabrata (= X. chinense ) is native to Central America and southeastern North America, and in recent times it has been introduced in other parts of the world, where in some cases it has become an invasive weed. It has sporadically been observed in Europe and in the Mediterranean area, mostly as a casual introduction and there is almost no evidence of stable populations. In Europe, other two species of X. sect. Xa...