Butterfly milkweed grows to about 2 feet in height with an upright habit. It is smaller in stature than common milkweed, with small narrow leaves that lack milky sap. It works well in a formal garden or a more naturalized setting. 'Hello Yellow' has flowers in round clusters borne at the tips of the stems, heralding the arrival of summer. Once the blooms have gone, ornamental seed pods appear, prolonging the visual impact of butterfly weed. With a tuberous root, it can be difficult to transplant and may take several years to bloom. Native to our Illinois prairies, iti is an outstanding sun-loving perennial for our gardens.