1808 Chamomilla suaveolens (Pursh) Rydb.

Syn.: Matricaria discoidea DC., M matricarioides (Less.) Port. p. p.

This species is now widely distributed in Eurasia and N. America. The origin does not seem to be quite clear but may be looked for in the Pacific region of E. Asia and northwestern N. America. It is well known that it has spread rapidly during the 19th and 20th centuries through N. America, Europe and partly Asia, probably more than the map shows, and even locally to S. America and New Zealand. The present distribution is almost circumpolar (Hultén, Circumpol. Il, p. 224, 388 and map 216).