Prairie Profile: Compass Plant

Prairie Profile: Compass Plant was originally published in the BFEC Newsletter, Vol. 13/No. 4, Fall 2009. 

The cover story of this newsletter describes prairies as ecosystems of statuesque grasses and flowering plants. The compass plant, which grows in the BFEC prairie and Wildlife Garden, is definitively towering with yellow flowers on stalks up to seven feet tall. Even more impressive are its 15 feet deep roots, which help it find water in the relatively hot, dry prairie climate. 

The flat, deeply lobed leaves of the compass plant display another intriguing tactic to limit water loss, for which is bears its unique name. Anyone who has noticed a field of sunflowers facing the same direction will recognize this trick: compass plant leaves rotate through the day according to the position of the sun. But rather than trying to maximize sun exposure, this rotation minimizes exposure by pointing the flat surface of the leaf away from the sun. As the sun sets in the west, the leaves (generally) face north and south, limiting heat gain and evaporation. Likely a very handy trick in the absence of abundant rainfall!

Is the compass plant accurate enough to guide you home should you be lost in a prairie? Let’s hope you’ll never have to find out.