Milkweed-Whorled (Asclepias verticillata)
Has very skinny, "whorled" leaves with clusters of white flowers that reached a height around 2'. Its foliage is valuable to butterfly larvae, especially monarchs, since it blooms late in the season. Likes hot dry soils, but tolerates moist garden soils. Perennial.
Mature plant in 1/2 gallon pot.