Teucrium

American germander, also called wood sage, is a widespread North American native perennial in the mint family that runs steadily underground on creeping rhizomes. From early to midsummer it sends up erect, softly hairy stems topped with one-sided spikes of pale pink-to-lavender flowers, each with the distinctive deeply lobed lower lip that gives the germanders their look and makes a generous landing platform for bees. It is a plant of moist open ground - wet meadows, streambanks, ditches, and the edges of thickets - across most of the contiguous United States into southern Canada, which tells you exactly what it wants: sun and a soil that does not dry out. The honest caveat is its vigor: those same rhizomes that fill a bank or a rain garden so readily will also colonize a tidy perennial border and crowd politer neighbors. Site it where it can run, or give it a root barrier, and it rewards you with a long, dependable bee-friendly bloom rather than a maintenance fight.

Tree germander is a fast-growing, spreading evergreen shrub native to the western and central Mediterranean, valued for its arching white-felted stems, aromatic grey-green foliage, and pale blue flowers that appear through summer. It thrives in full sun on free-draining alkaline soils and makes a handsome wall shrub, informal hedge, or silver-foliaged accent in warm-climate gardens. The honest catch is its sprawling ambition: specimens routinely reach 13 feet wide - far exceeding what most gardeners anticipate - and the plant is frost-tender below 23°F (USDA zone 8b), collapsing to the ground in a hard freeze without reliable wall shelter.

Wall germander (Teucrium chamaedrys) is the classic low edging and knot-garden sub-shrub of the formal Mediterranean garden - a tough, drought-loving evergreen that clips as neatly as a tiny hedge. It carries small, glossy, dark-green, scalloped leaves shaped like miniature oak leaves, and through summer it lifts short spikes of rose-pink to purple two-lipped flowers that bees work steadily. Native across Europe, the Mediterranean, and into western Asia (POWO, Kew), it is built for hot, dry, sun-baked ground and sharp drainage: it rots in wet or rich soil and is at its best on a lean bank, a hot border edge, or a clipped knot. Honest caution (load-bearing): although wall germander has a long folk-medicine history, it is now known to be HEPATOTOXIC and has caused serious liver damage when taken as a herbal remedy or slimming tea - so it is NOT safe to consume. Grow it strictly as an ornamental.