Physostegia virginiana aka Obedience

Physostegia virginiana is a perennial in the mint family. Gardeners call it obedient plant or false dragonhead. Its native range runs from Canada to northeastern Mexico. It grows in wet meadows, prairies, and along streams. It also grows in damp woods and thickets. The name refers to blooms that stay put when moved.

This plant forms clumps and spreads through underground rhizomes. Garden plants reach about 2–4 feet (0.61–1.22 metres) tall. Clumps can spread 2–3 feet (0.61–0.91 metres) wide. RHS gives smaller sizes, down to 1.6 feet (0.5 metres) tall. Its listed spread starts at 0.3 feet (0.1 metres). The green stems stand upright and may branch. They have smooth surfaces and a square cross-section. Pairs of green leaves grow along each stem. The leaves are narrow, with sharp teeth along their edges. The plant loses its leaves for winter.

Pink to pale purple flowers grow on upright spikes. White blooms occur too. Each tubular flower has two lips and a swollen throat. The upper lip curves over the flower's opening. Three lobes form the spreading lower lip. Flowers open from the base toward the spike's tip. Bloom dates vary among sources, from June through October. The flower spikes reach 1–1.5 feet (0.30–0.46 metres) long. Fruit appears from August through November. Bees, butterflies, and hummingbirds visit the flowers. The blooms also suit cutting for indoor use.

Give this plant full sun and soil that stays moist. It also grows in part shade and tolerates wet soil. Good drainage suits it best. It accepts clay, loam, sand, and chalk. Sources support acid, neutral, and alkaline soil. Water needs are moderate. Most sources list USDA zones 3–9; NC State includes zone 2. RHS rates it H7 for UK hardiness. Use it in borders, cottage gardens, meadows, or rain gardens. Deer tend to leave it alone.

Fast growth can make this plant hard to contain. Rich, damp soil can lead to strong spread. Divide clumps every year or two to limit their reach. Shallow roots make unwanted shoots easy to pull. Stems may lean in rich soil, shade, or summer heat. Tall plants may need stakes. Remove old stems in winter. Aphids, spider mites, slugs, and snails may cause trouble. Disease risks include rust, blackspot, and fungal or bacterial rots. The supplied sources do not establish edibility or toxicity.