This four to ten-foot plant has big flowers and odd leaves.
The leaves are 8″ long and 5″ across and grow opposite each other on the stem. The most amazing thing is that they are joined at the base to form a cup that’s large enough to hold water.
You can see the outside of the cup in this photo (red arrow). Click here to see the inside.
The leaves gave the plant its name: Cup plant (Silphium perfoliatum).
Why a cup?
Perhaps it prevents insects from climbing the stem to the flowers.
But flying things can reach it. Goldfinches love the seeds.
(photo by Dianne Machesney)
I wonder if this is a second evolutionary mechanism for gathering and absorbing moisture (through the stem in addition to the roots). Such a large plant must require an enormous amount. Just a guess. Nice birdbaths for hummingbirds, though.
They say that’s perfoliate.