Named for the cup-shaped vase where leaves join the stalk, these tall perennials hold water between rains for insects, amphibians, birds, and small mammals. Flowers are sunflower-like, and plants occur in woods and thickets, meadows, along prairie streams and railroad tracks throughout the Midwest. Stems 4-8’ tall are distinguished by square stems and pairs of cup-forming leaves. 3” flower heads. NATIVE TO THE EASTERN HALF OF THE U.S.