Examples of Taraxacum species (sect. Ruderalia) that have a well-known main distribution area and, a few rather isolated, obviously introduced occurrences, are given. The lack of a long tradition of specific knowledge and collection of Taraxacum sect. Ruderalia specimens have impeded our understanding of the origin of the present distributions. Some views are presented. Taraxacum ancistratum, T. crassum, T. deltoidifrons, T. infuscatum, T. jugiferum, and T. lundense, all belonging to Taraxacum sect. Ruderalia, are described as new species. Three or four of these species were first found as introductions far away from their supposed main distribution area.