Central to cuisines the world over, cilantro is an annual herb native to Iran. All parts of the plant are edible, including the root, but it is most commonly used for its leaves, used fresh as a garnish, and for its seeds, which are commonly toasted and ground and are known as coriander. Cilantro prefers rich, well-draining soil and will turn bitter in very hot weather, so consider planting it in a container for your porch or kitchen.