Russian sage

Arkansas blue star (Amsonia hubrichtii), also called threadleaf bluestar or Hubricht's bluestar, is a clump-forming native perennial from a tiny wild range in the Ouachita Mountains of Arkansas and Oklahoma that has become one of the most dependable foliage perennials in temperate gardens. It builds a soft, rounded, knee-to-waist-high mound of upright stems clothed in very fine, needle-like, thread-thin leaves, so the whole plant reads as a feathery green cloud through summer. In late spring the stem tips carry loose clusters of small, pale powder-blue, five-pointed star flowers, a quiet but pretty show that draws butterflies and other pollinators. Its headline act comes in autumn, when the fine foliage turns a clear golden-amber that lights up the border and earned it the Perennial Plant Association Plant of the Year for 2011. It wants full sun to part shade and is famously tough, adaptable, and deer-resistant, though it will flop open in too much shade or overly rich soil, so give it sun and a light shearing after bloom if you want it to stay upright.

A long-lived native perennial of central and eastern US woodland borders and prairie meadows with deep blue pea-shaped flowers in late spring, blue-green leguminous foliage, attractive black seed pods for winter interest, and a nitrogen-fixing root system (Fabaceae). Larval host for 6 documented butterfly species per NC State (orange sulphur, clouded sulphur, frosted elfin, eastern tailed-blue, hoary edge, wild indigo duskywing) - among the highest Lep-host-count perennials in the eastern flora.

An architectural, branching perennial grown for the metallic steel-blue flush it takes on in summer: small, egg-shaped flowerheads, each ringed by a collar of spiny, silvery-blue bracts, are held on rigid, blue-tinted stems above a basal rosette of leathery, heart-shaped leaves. It is a tough, genuinely drought-tolerant plant for hot, dry, sharply drained, even poor sandy or gravelly soil in full sun - it resents rich, wet ground, where it rots and flops - which makes it ideal for gravel gardens and coastal, seaside plantings, and one of the best long-lasting cut and dried flowers. At the height of summer it is a magnet for bees, butterflies, and hoverflies. It is grown purely as an ornamental and is not eaten.

A Mediterranean-native evergreen subshrub for sunny edges, pollinator beds, and low-water garden structure. The source of true oil of lavender; well-loved but at times difficult to grow east of the Mississippi because it does not tolerate wet feet or heavy clay.

A tall, sun-loving, drought-tolerant perennial in the daisy family, grown for its broad, flat-topped corymbs of tiny golden-yellow flowers held on stiff stems above finely divided, aromatic gray-green ferny foliage. Native to the Caucasus, Iran, and Afghanistan and long naturalized in gardens worldwide, it forms a tidy upright clump (rather than running like common yarrow) and is one of the most reliable, low-care pollinator and cut-flower plants for hot, dry, full-sun borders.

An architectural clump-forming perennial grown for its striking spherical, metallic steel-blue flowerheads - drumstick "globes" held on tall stems above spiny, deeply cut grey-green leaves that are white-woolly beneath. It blooms in mid to late summer and is one of the very best garden plants for pollinators: at the height of summer the blue globes are smothered in bees and butterflies. Genuinely drought-tolerant, it thrives in poor, dry, sharp-drained soil in full sun, where it earns its place as bold summer structure and stands well into winter as dried seedheads that feed goldfinches and other small birds.