Wednesday, August 01, 2007

Cup Plant (Silphium perfoliatum)


Few forbs represent the Midwestern tallgrass prairie as well as the plants of the genus Silphium. The compass plant, Silphium laciniatum, served as an orienteering device for early explorers: the tall, deeply cut leaves are oriented to turn north and south based on the sun's direction in order to conserve water. Prairie dock, Silphium terebinthinaceum, towers several feet over the rest of the prairie when it blooms in the early fall. At an average height of 12 feet, Cup plant, Silphium perfoliatum, thrives in the wet draws of prairie, often occupying the same areas as the dense, woody sumacs and rough leafed dogwoods.

Last winter, as part of my effort to restore a small patch of prairie to an area with "prairie" in the town's name, I bought two big pots of black soil fromMissouri Wildflowers. In fact, I bought a whole truckbed full of what looked like pots of soil devoid of plants. As soon as the first leaves appeared (four months later), I quickly planted all of my perennials, thick masses of rootstock with little vegetative growth. Having worked in horticulture for a few years, I learned the hard way that the best treatment of native wildflowers is no treatment. If you actually take care of native plants, they'll send out nothing but vegetative growth and few flowers. Therefore, I never water or fertilize my prairie plants and they reward my lack of effort with enormous stalks and prolific blooms.

Until a few years ago, prairie plants weren't given proper bidding. The medicinal uses of Amazonian rainforest plants were well known, even discussed in mainstream media. Prairie continued to be a neglected habitat, respected only by a handful of botanists and historians who recognized the ethnobotanical virtues of prairie and the value of historic landscapes. Thanks to the tireless efforts of the Nature Conservancy, the National Wildlife Federation, the author William Least-Heat Moon and several other individuals and non-profit organizations, prairie is now respected as a viable landscape worthy of our protection.

To win the American public's support of prairie, economic values of prairie had to be discovered and advertised. Prairie proponents capitalized on the medicinal and traditional Native American uses of prairie plants. For example, the plants of the genus Silphium are collectively called "rosinweeds;" when the top of any of the rosinweeds is broken off, a sweet smelling, clear, resinous sap pours out. Several tribes used the dried resin as a chewing gum. The Winnebago tribes believed S. perfoliatum had supernatural powers; braves drank a tea made of the rhizome before setting out on a buffalo hunt. The Winnebago believed that the plant purified their souls. The Chippewa used part of the plant's root to stop hemorrhaging from the lungs, to alleviate back and chest pains and even excessive menstrual bleeding. Over 203 prairie plants have been identified as having been used as medicine by Native American tribes. 78 different types of disease have been traditionally treated by different prairie plants.

Based on ethnobotanical history, modern researchers are investigating the medicinal properties of prairie plants. The sap from S. perfoliatum not only provides protection from HIV in infected cells, but is a known anti-cancer organic extract. The healing properties of the genus Echinacea are well known, as are the anti-cancer treatments afforded by the genus Ceonanthus.

S. perfoliatum stands tall in the yard, taller even than my bluestems and switch grass. The leaves of the plant are arranged in a perfoliate fashion, which means the leaves wrap around the entire stem, creating a small cup which captures the morning dew and rainfall. Considering that the last appreciable rain occurred June 21, the morning dew collected in my prairie plant serves as the only water source in the area for all of the local butterflies.

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