There are about 65 species in this genus of generally low growing annuals and herbaceous perennials. They are native to Europe, Asia and Africa with two coming from Australia. The name comes from the Greek words "not" and "yoke" in reference to the undivided calyx of the flowers which is actually a single sepal.

Ajugas may great ground covers with foliage ranging from green to purple to variegated types. The flowers can be attractive but they are a minor part of the plant's appeal. Although not truly invasive, ajugas will continue to move out from the original plants. It may take a little work each spring to cut them back to the desired coverage.