Silphium perfoliatum (Cup Plant)
|Also known as:|
|Life cycle:||short-lived perennial|
|Habitat:||part shade, sun; moist; prairies, along shores, wetlands|
|Bloom season:||July - September|
|Plant height:||3 to 8 feet|
|Wetland Indicator Status:||GP: FAC MW: FACW NCNE: FACW|
|MN county distribution (click map to enlarge):|
|National distribution (click map to enlarge):|
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10 to 30 stalked flowers at the tip of the branching stems and arising from upper leaf axils. Flowers are 2½ to 3½ inches across with 17 to 35 yellow petals (ray flowers) that are fertile and have a split style protruding from the short tube at the base. The center disk is green until the disk flowers bloom; disk flowers are sterile, yellow, tubular with 5 triangular lobes and a column of brown stamens with long, stringy style-like yellow tips. Bracts are in 2 or 3 layers, the outer bracts broadly egg-shaped with pointed, flaring tips, the inner bracts smaller and subtending the ray flowers. Flower stalks and bracts are smooth to rough.
Leaves and stem:
Basal and lowest stem leaves drop off early, withered away by flowering time. Stem leaves are very large, to 10 inches long and 6 inches wide, opposite pairs joined together at the stem (perfoliate), forming a cup (hence the name). Leaves are coarsely toothed, pointed at the tip, and feel rough. Lowest leaves narrow at the base to a broadly winged stalk.
The perfoliate leaves and stout, square stem make Cup Plant easy to identify. It can create colonies from short, fibrous rhizomes and has become invasive in New England where it's been introduced. Cup Plant is a magnet for red aphids, which can be found in masses on the undersides of leaves, and subsequently become lodging for parasitic wasps and food for predatory insects as well as baby hummingbirds. No insecticide required! There are 2 recognized varieties: var. connatum, which has variously hairy stems and is only known from a few Mid-Atlantic states in the New River Valley, and var. perfoliatum, present in much of the central US, including Minnesota.
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- Cup Plant
- Cup Plant plants
- Cup Plant plants
- a small stand of Cup Plant
- garden-grown Cup Plant
- spring growth
- red aphids on Cup Plant leaves
- flower cluster
Photos by K. Chayka taken in Ramsey and Hennepin counties. Photos courtesy Peter M. Dziuk taken in Anoka County and in a private garden in Lino Lakes.
Have you seen this plant in Minnesota, or have any other comments about it?