View photos of the medicinal plant Arnica cordifolia (Heartleaf arnica), profiled in Medicinal Plants of the Western Mountain States.

A passage from Medicinal Plants of the Western Mountain States:

Apply Arnica salve, ointment, or liniment to poorly healing sprains, muscle pulls, contusions, and bruises, all with unbroken skin. One exception is the diluted ointment – use it on bedsores, poorly healing wounds, post–operative incisions, and other breaks that would benefit from the plant’s tissue stimulation and healing properties. A frequently overlooked application, Arnica is often found calming to arthritis pain, especially if it is aggravated by the cold.