The leaves of the hyssop plant vary in size depending on the hyssop variety. For instance, the anise hyssop has small leaves that are only about 4 inches long and 2 inches in width while the leaves of the yellow giant hyssop can grow up to 6 feet long and 3 inches wide.
The leaves of each variety of hyssop are distinctive. For example, the leaves of the blue giant hyssop are shaped like a heart and have a strong anise-like smell. Conversely, purple giant hyssop leaves are oblong, have a thin texture and are connected with stalks that have fine hairs.
Hyssop leaves are safe to use in cooking, and give savory dishes a rich, minty flavor. The leaves have a very strong taste, however, and shouldn't be used with the hyssop flower, as the leaves will overpower the flower's flavor. Hyssop leaves can also be made into a tea or ground into a poultice to treat scars or cold sores.