Easier to grow than the European Arnica montana, it has been found to be just as useful in treating inflammations, bruises, burns, and sprains when applied externally. Traditionally used to boost circulation and treat angina, taking it internally is discouraged now as it is fairly toxic. Recent research shows it strengthens the immune system. Pretty 2" yellow-rayed daisy-like flowers. Prefers full sun and damp acidic soil where it will spread rapidly from underground stems. Native from California to South Alaska, Wyoming, Colorado, and Canada.