Amsonia

The blue stars, originating from North America, Japan and the Mediterranean, provide in late spring through into summer, blue-sky starry flowers on delicate stems. For contrast their emerge from darker, dusky buds. Foliage is often narrow and can produce golden autumnal tones. It's part of the Apocynaceae family, so can produce a milky sap (wear gloves when handling) when stems or leaves are broken. Amsonia is named after Charles Amson, an 18th century, scientific American explorer.