This spice tastes and smells like a pungent version of nutmeg, and for a very good reason: mace is the bright red membrane that covers the nutmeg seed. After the membrane is removed and dried, it becomes a yellow-orange color. It's sold ground and, less frequently, whole (in which case it's called a blade). Mace is used to flavor all manner of foods, sweet to savory.
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.