Flavonoid variation in Arnica subgenus Arctica

Twelve flavonoids (including seven flavonol and three flavone glycosides, one flavone aglycone, and one unknown) were isolated from the leaves of 198 populations of the seven species comprising Arnica subgenus Arctica. Flavonoid profiles are relatively simple, with two to six compounds found per population; however, considerable flavonoid variation was apparent in populations of A. angustifolia, A. frigida and A. lonchophylla. In subgenus Arctica, flavonoid diversity appears to have accompanied high morphological variability. Leaf flavonoid chemistry supports the hypotheses that A. fulgens and A. sororia are very closely related, and A. rydbergii probably represents the most advanced species within the subgenus. Only A. rydbergii is clearly delimitable on the basis of its fiavonoid chemistry. The absence of any highly derived or methylated flavonoid suggest the subgenus Arctica probably represents the most ancestral subgenus in Arnica.