Mullein is a native plant, which favors dry, rocky soil and full sunlight, and is found throughout the US. An easy way to spot patches of this plants in cold weather is to look for the chocolate brown skeletons of the second-year plants. Look for 4- to 6-foot-tall stalks, which often have branching flower heads that resemble the arms of a saguaro cactus. The part you want for medicine are the velvety green leaves, which can still be found in winter growing in basal rosettes on one-year-old plants. Treat head colds by crushing the leaves into boiling water and breathing the steam. This medicated vapor acts as a decongestant.