Silphium laciniatum | |
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Conservation status | |
Scientific classification | |
Kingdom: | Plantae |
(unranked): | Angiosperms |
(unranked): | Eudicots |
(unranked): | Asterids |
Order: | Asterales |
Family: | Asteraceae |
Tribe: | Heliantheae |
Genus: | Silphium |
Species: | S. laciniatum |
Binomial name | |
Silphium laciniatum L. |
Silphium laciniatum (Compass Flower, Compass Plant or Rosinweed) is a species of flowering plant in the genus Silphium. It is native to east-central North America, from southern Ontario and New York south to Alabama and west across the prairies to North Dakota and Colorado south to Texas.
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It is a perennial herbaceous plant similar in appearance to a sunflower, growing to 1-4 m tall, with bristly-hairy stems. The leaves are alternately arranged, and deeply pinnately lobed; the basal leaves up to 40 cm long, becoming smaller higher up the stem. The flowers are produced in flowerheads (capitula) 5-12 cm diameter, with a ring of ray florets surrounding the 2-3 cm diameter center of disc florets. Flowering is in late summer, typically from July to September.
Compass plants are so named because they tend to align their foliage North - South to present the minimum surface area to the hot noon sunshine. The taproot of the compass plant may grow to more than 9-14 ft. deep, making it hardy and resistant to drought.
The plant was used in Native American herbal medicine as a vermifuge, and to treat coughs and asthma.Cultural
Aldo Leopold devotes much of the July entry in _A Sand County Almanac_ to Silphium -- its hardiness, but its slow disappearance nevertheless. "It is easy now to predict the future. For a few years my Silphium will try in vain to rise above the mowing machine, and then it will die. With it will die the prairie epoch.”