Stachys
Most notably the lamb's ears are one of the mainstays of the drought resistant garden. Forming dense silver ground cover in the driest of soils. On the other hand S. macrantha and S. officinalis prefer better soils in sun or part shade and make ideal border perennials. Powdery mildew can be an issue with the silver-leaved forms but doesn't seem to do any long term damage.
As with most members of the mint family, the tubular, two-lipped flowers are designed to restrict access to the nectar to specific groups/sizes of pollinators: those of Stachys attract primarily honeybees and bumblebees. The border perennial types support the larvae of a number of moths, while the furry-leaved lamb's-ear types are some of the species used in nest-building by the attractive wool carder-bee: female bees bite the hairs off the leaves, roll them into a ball and take them to a nest-hole where they are fashioned into a breeding cell. In contrast, males spend much of their time defending suitable plants against all-comers in an attempt to persuade the females that 'their' hairy leaves are the best!