prairie compass plant, pilotweed, polarplant, gum weed, cut-leaf silphium, turpentine plant

Description:

The common name compass plant was inspired by the "compass orientation" of its leaves. The large leaves are held vertically with the tips pointing north or south and the upper and lower surfaces of the blades facing east or west. A newly emerging leaf grows in a random direction, but within two or three weeks it twists on its petiole clockwise or counterclockwise into a vertical position. Studies indicate that the sun's position in the early morning hours influences the twisting orientation. This orientation reduces the amount of solar radiation hitting the leaf surface. Vertical leaves facing east-west have higher water use efficiency than horizontal or north-south-facing blades. Early settlers on the Great Plains could make their way in the dark by feeling of the leaves. This plant is a taprooted perennial herb producing rough-haired stems usually one to three meters tall. The leaves are variable in shape and size, being 4 to 60 cm (1+1⁄2 to 23+1⁄2 in) long and 1 to 30 cm (1⁄2 to 11+3⁄4 in) wide. They are hairy, smooth-edged or toothed, and borne on petioles or not. The back of the flower head has layers of rough, glandular phyllaries. The head contains 27 to 38 yellow ray florets and many yellow disc florets. The fruit is a cypsela which can be almost 2 cm (3⁄4 in) long and is tipped with a pappus of two short awns.

Habitat:

Hadley Valley Preserve is former farmland that has been restored to mostly native prairie with some clumps of shrubs and forest. There is a nice size creek bisecting it. The 807-acre Hadley Valley was acquired between 2000 and 2014. The preserve is part of the Spring Creek preservation system, which conserves more than 2,000 acres. Hadley Valley protects a diversity of habitats, including forest, savanna, wetland and a portion of Spring Creek. Wildlife found at the preserve includes more than 15,000 species of insects, birds, aquatic invertebrates, fish, mammals, amphibians and reptiles. The preserve is also home to a variety of plant species, including tall swamp marigold, wahoo, great angelica, yellow avens and shingle oak. The site is managed with invasive species control, prescribed burning, native species establishment and soil stabilization to protect and enhance its natural resources. The preserve is the location of the largest restoration effort in the District’s history — a stream de-channelization, wetland restoration and wildlife habitat restoration project in 500 acres of the preserve — performed in partnership with the Illinois State Toll Highway Authority, Openlands, U.S. Army Corps of Engineers, and the O’Hare Modernization Program.

Notes:

compass plant is very beneficial to native prairie environments, not only for the insects they feed and house, but also the deep and long root systems which benefit the soil.