There are 2 different species of Arnica which are used medicinally. This is the easier species to grow throughout most of the U.S, rather than the high elevation European species, A. montana. It is native to the northwestern U.S., with beautiful little yellow daisy flowers. The flowers are the medicinal portion of the plant. It can be found in many over the counter medications for bruises, aches, arthritis and swelling. It is used externally only, as it can be toxic if ingested. Grow in sun in well drained soil.