Silphium perfoliatum
| Cup plant | |
|---|---|
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| Scientific classification | |
| Kingdom: | Plantae |
| (unranked): | Angiosperms |
| (unranked): | Eudicots |
| (unranked): | Asterids |
| Order: | Asterales |
| Family: | Asteraceae |
| Tribe: | Heliantheae |
| Genus: | Silphium |
| Species: | S. perfoliatum |
| Binomial name | |
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Silphium perfoliatum L. |
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Silphium perfoliatum, the cup plant or cup-plant, is a species of flowering plant in the family Asteraceae, native to eastern and central North America. It is an erect herbaceous perennial with triangular toothed leaves, and daisy-like yellow composite flower heads in summer.
The specific epithet perfoliatum means "through the leaf."
There are two varieties:-
The typical height of this plant ranges from 1–2.5 m (3–8 ft). The stem is stout, smooth, slightly hairy (glabrous) strongly 4-angled (square), like mint plants. The leaves are opposite, toothed and ovate. The petioles are widely winged and fused around the stem, forming a cup. The first flower develops on the tip of the main stem, then more flowers develop on side branches.
No other species of Silphium in Michigan have fused leaf bases.
The flowers, which appear from midsummer to autumn (fall), look very similar to sunflowers, measuring about 2.5 cm in diameter, with golden yellow ray florets. In the middle of the flower there are small, sterile, tubular disk florets, which are structurally bisexual, but the stamens are the only fertile part, and they do not produce fruit. The corollas are tubular, 5-toothed, and the style is undivided.
The ray florets have female characteristics, and eventually develop to become thin brown achenes with a marginal wing utilized for wind dispersal.
Insect pollinators including bees, butterflies, and skippers help to cross-fertilize flowers to produce seeds. 20 to 30 seeds are created in each flower head. Each seed is about 9 to 15 mm long, 6–9 mm wide, flattened in shape, with a thickness of 1 mm.
Silphium perfoliatum is able to establish colonies due to its central taproot system and shallow rhizomes. A multi-rhizomed clone originating from a single seed is believed to be 15 years old. The roots found in botanical gardens have been estimated to be more than 50 years old. The plant has an extensive root system and does not transplant well except when very young.
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Wikipedia