Flowerheads of Arnica montana, A. chamissonis ssp. foliosa, A. amplexicaulis and A. sachalinensis contained, in addition to the pyrrolizidine alkaloids, tussilaginic acid and isotussilaginic acid, 2-pyrrolidineacetic acid and the C-1 epimers of the two pyrrolizidine acids. Biosynthetic aspects are discussed on the basis of this co-occurrence. The pyrrolizidines tussilagine and isotussilagine, formerly reported for Asteraceae species, are artefacts caused by Soxhlet extraction with methanol. © 1992.