Amsonia tabernaemontana var. salicifolia has norrow willow-like foliage. 
It is an elegant perennial with a neat, rounded form,the foliage is lime-green when it emerges, becoming dark green in summer, and producing excellent fall color with shades of gold. In spring, the plants display a profusion of delicate, pale blue star-shaped flowers on terminal clusters. use by many garden designer in the UK and the USA.