Cup plant
Silphium perfoliatum
Silphium perfoliatum
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Sun/shade: Full sun
Soil moisture: Medium to wet
Height: 4-8'
Spread: 1-3'
Flowering period: July to September
Host plant for 6 caterpillar species
Few plants can rival the dramatic architecture of cup plant, whose concave adjoining leaves capture rainwater to form a vertical series of pools along a central, towering stem. The pools present a rare form of wildlife value, serving as a water source for birds, pollinators, and other organisms. In mid to late summer, a loose panicle of yellow flowers forms at the plant’s apex, providing a beautiful complement to a backdrop of blue skies – a vision which is all the more noticeable since few plants overtop cup plant. The pollinator value of the plant’s flowers is such that the Xerces society has selected cup plant for its short list of recommended pollinator plants for the Great Lakes region. After the growing season is over, cup plant’s hollow stem continues to serve as nesting habitat for leafcutter bees.
Native to NE Ohio habitats including wet meadows, woodland edges, and the margins of water bodies, cup plant grows well under conditions of wet to average soil moisture and full sun to partial shade. In keeping with its imposing stature (up to 10’ tall), cup plant can be quite dominant, frequently forming colonies through growing via numerous rhizomes. If intermingled with other plants as a mixed planting in the garden, cup plant may take over. It thus may be best to plant cup plant in a discrete patch that is spaced apart from other plants.
Photo by Ashley Keesling.
