Cup Plant
Silphium perfoliatum

Courtesy Julie Makin, Lady Bird Johnson Wildflower Center
Summary
Cup plant (Silphium perfoliatum) is hard to miss, growing up to 9 feet tall. At the SBG, it can be seen lining the path from the parking area to the demonstration gardens, and throughout the meadow.
A member of the Asteraceae family, this statuesque specimen boasts bright yellow blooms, and birds love the seeds that follow. The resinous juices they possess inspired the genus name Silphium, which is derived from the Greek word ‘silphion’. Silphion, a North African plant with a resinous juice used for medicinal purposes, was so prized that the plant appeared on ancient Greek coins. Juices aside, an easy way to identify cup plant is by its leaves: Rub one between your fingers, and you’ll immediately notice the unmistakable, sandpapery feel.
Silphium grows easily from seed, and is at home in a wide variety of soils, even difficult clay soil. If you like your native plants on the large side, and have room for them to roam, cup plant is for you!
More Details
FAMILY
Asteraceae (Aster)
BLOOM TIME
July-August
FLOWER
Yellow
MATURE SIZE
5-9 feet
LIGHT REQUIREMENT
Full Sun
SOIL CONDITIONS
Medium to wet
NATIVE STATUS
PA Native
Ecosystem Connections
The common name ‘cup plant’ refers to the leaves that clasp the stem, forming cups that collect rainwater, and it’s common to see birds drinking from these cups. It also produces seeds which are enjoyed by many songbirds. The flowers attract many pollinators, including honey bees, bumble bees, and big showy butterflies. Soldier beetles and adult fireflies are unexpected but common visitors, and it’s a host plant for caterpillars of the silphium moth. Leafcutter bees use broken, hollow stems of cup plant as nesting sites.