Cup plant

Description:

Silphium perfoliatum is an herbaceous perennial. A typical height this plant grows ranges from 1-2.5 m. The stem is square and glabrous. The stout, smooth, slightly hairy stem is strongly 4-angled. The leaves are in an opposite arrangement. The leaves are toothed and ovate leaf shape.The petioles are widely winged. The petioles’ base is at the stem and it is fused with its opposite in its pair that form a cup where the stem is located.

Habitat:

open meadow

Notes:

I spotted this at Baden Powell park. The plants were almost 6' tall.