The word "herb," as used in "herbal medicine," means a plant, or plant part, used to make a medicine, flavor, aromatic oil or fragrance. An herb can be a leaf, flower, stem, seed, root, fruit, bark or any other part of a plant. It is estimated that there are approximately 500,000 plant species on earth today with only 5,000 being studied in any extensive way. According to Dr. Norman Farnsworth, "Considering that 121 prescription drugs come from only 90 species of plants, and that 74% of these were discovered following up on native folklore claims, a logical person would have to say that there may still be more jackpots out there."