The echinacea sold in drugstores comes in a wide range of liquids, pills, powders, and tinctures, which can be derived from some combination of the plant's root, flower, or stem.

CNN: Echinacea fails to curb the common cold (again)

But new research found that, like stem rust, stripe rust increases its genetic variability by reproducing sexually on the leaves of another host plant (the barberry), making itself more adaptable and more deadly.

ECONOMIST: Wheat rust and world farming