Thursday, August 9, 2012

Compass Plant

Compass Plant (Silphium laciniatum ) is an impressive prairie wildflower, with yellow flowers growing on stalks that can be over 8 feet high.  The flowers are similar to those of other Silphiums, like the Cup Plant, but the Compass Plants leaves are distinctive.  The two-foot long, deeply cut leaves create a striking profile for this plant even without its tall flowerstalk.  The leaves also give the Compass Plant its name since they tend to align on a north-south axis.  Research by botanists at Iowa State provides evidence that this leaf orientation uses sunlight and water most efficiently.  Deep roots (over 12 feet long [pdf]) allow the compass plant to thrive even during dry summers. 

Compass Plant is listed as a Threatened species in Michigan.  It is more widely distributed in the central and plains states.  The plants pictured here were blooming at the Kalamazoo Nature Center's restored prairie.

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