Silphium laciniatum

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.

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 and 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.