Silphium perfoliatum (Cup Plant)

Silphium perfoliatum

Silphium perfoliatum L.

Cup Plant, Indian Cup, Ragged Cup, Carpenter Weed

Kingdom	Plantae	Plants, but not fungi, lichens, or algae
Subkingdom	Tracheobionta	Vascular plants—plants with a “circulatory system” for delivering water and nutrients
Division	Magnoliophyta	Flowering plants, also known as angiosperms
Class	Magnoliopsida	Dicotyledons—plants with two initial seed leaves
Subclass	Asteridae	A large class that encompasses asters
Order	Asterales	Flowering plants with a central disk flower and surrounding petals, like daisies
Family	Asteraceae	The aster family, which also includes daisies and sunflowers; from the Greek ἀστήρ, “star,” for the star-shaped flowers
Genus	Silphium
Species	perfoliatum	Refers to the stem which “perforates” the leaf

About plant names...

Cup plant, named for the cup-shaped depression formed where opposing leaves meet the stem, is another member of the very large aster family. It is a North American native.

Identification: Plants are 4-10' (1.2-3 m) tall, on single stalks that branch only near the flowering top. They could be mistaken for a type of sunflower, except for the unusual leaves. The stem is thick and hairless, four-sided, and green or purple. Leaves are opposite, joined to each other at the stems, producing a depression between them that holds water. The trapped water often attracts birds. Leaves are rough to the touch, and coarsely toothed. Flowers have a dark yellow central disk surrounded by 18-40 bright yellow petals (“ray florets”). They appear from July to October. Fruits are egg-shaped achenes ¼-½" (7.6-12 mm) long, with wings.

From Britton, Nathaniel Lord, and Brown, Addison, An illustrated flora of the northern United States, Canada and the British Possessions, 1913; scanned by the Natural Resources Conservation Service.