Amsonia

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.

Also called blue star, willow amsonia or woodland bluestar, this is a native perennial of the dogbane family from the eastern and south-central United States, where it grows in moist, sandy or rocky open woods, thickets, stream banks and ditches. It makes an erect, rounded clump of leafy stems 2 to 3 feet tall and wide, topped in spring by clusters of small, pale blue, star-shaped flowers and followed by slender, bean-like pods. The narrow, willow-shaped leaves may turn yellow to golden in fall. It grows slowly and stays where it is planted, and NC State Extension and the Missouri Botanical Garden both list it as tolerant of deer and drought: its stems and leaves carry a milky latex that herbivores avoid.