Thought by 1st-century Romans to be a good luck symbol, dill has been around for thousands of years and has a long history of culinary as well as medicinal uses. This annual herb grows up to a height of about three feet and has feathery green leaves called dill weed, marketed in fresh and dried forms. The distinctive flavor of fresh dill weed in no way translates to its dried form. Fresh dill does, however, quickly lose its fragrance during heating, so should be added toward the end of the cooking time. Dill weed is used to flavor many dishes such as salads, vegetables, meats and sauces. The tan flat dill seed is actually the dried fruit of the herb. Heating brings out the flavor of dill seed, which is stronger and more pungent than that of the leaves. It's most often used in the United States as part of the pickling mix in which dill pickles are cured.
From The Food Lover's Companion, Fourth edition by Sharon Tyler Herbst and Ron Herbst. Copyright © 2007, 2001, 1995, 1990 by Barron's Educational Series, Inc.