| a hardy composite plant, Silphium perfoliatum, of eastern North America, having large yellow flower heads and opposite leaves that envelop the stem, forming a cup. |
| cup plant n. A coarse perennial herb (Silphium perfoliatum) in the composite family, native to the central and southeast United States and having showy radiate flower heads of yellow flowers and opposite leaves whose bases fuse to form a cup around the stem. |