Whorled milkweed (Asclepias verticilata) is a 1-3 foot deciduous, native, herbaceous perennial wildflower. It grows in average, well-drained soils in full sun but can tolerate poor or dry soils. It propagates easily by seed or root cuttings and will naturalize in the garden, taking up quite a bit of space. 

In summer, five-petaled flowers bloom with up to 100 flowers per cluster and one to three clusters per stem. Fragrant flowers in colors of green, pink, white, and purple or lavender will last from June through August.