entire, laciniate, pinnatifid
June - October
1.0 - 3.0
Separated from other large yellow composites by its large, wide, oak-like leaves, which are reported to point north and south with the leaf surface facing the morning and afternoon sun. The leaves are a foot long and one half foot wide. The taproot may grow to a depth of 8-15' in the Midwest (Weaver 1968). Members of the genus Silphium are easily distinguished by their large, stiff phyllaries and stems covered with very stiff hairs.
Occurs in wet mesic to dry mesic areas in soils with a pH range of 4.5-7.5. Clay soils are prefered, but it is adaptable to better drained soils. Seeds should be collected in fall (September - October) and planted 1/2" deep in either fall or early spring. Stratification at 33-40 degrees F is reported to inprove germination (Steffen 1997). Seedling grow slowly and often do not bloom for 3-4 years. There are 10,400-33,000 seeds/lb and the recommended planting rate is 25 lbs/acre. Transplanting has been very successful for large plants with new plants often growing from peices of taproot left in the ground. Seedlings, however, are easily killed by breaking the taproot.
Desirable to cattle as forage. Deer browse the foliage, songbirds love the seeds and butterflies (particularly sulphurs) frequent the flowers.
Compass plant is abundant throughout the United States in prairies which receive 30" or more rain (Philips Petroleum Company 1955). It occurs on prairie remnants, roadsides, and along railroads. Readily eaten by all classes of livestock, it is nutritious, especially the new growth early in the season. It is a decreaser when overgrazed and is an indicator of overgrazing. When flowering, a gummy material appears on the upper one-third of the main stem. This gum was reported to be chewed by Indians. The leaves face north and south giving "compass plant" its common name. Members of the genus Silphium tend to hybridize making their taxonomy difficult.
Along railroads and in prairies.