Cup plant (Silphium perfoliatum) belongs to the family Asteraceae (the Aster family). It is a perennial herb that is native to eastern and central North America. It grows in prairies, open woodlands, on stream banks, and can reach 1.2-2.4 m in height. The stems are four-angled. The leaves are elliptic, toothed, and arranged in opposite. The bases of upper leaves are united in a cup. The flower-heads are 5-7.5 cm across with 18-40 yellow or pale yellow ray florets. They bloom from July to September.