Compass Plant

Compass Plant head inflorescence

Compass Plant head inflorescence

Silphium laciniatum, commonly called Compass Plant is a native Missouri plant found in the Asteraceae family.  Compass Plants can reach heights of 3 meters or more.  They have a head inflorescence, typical of members of the Asteraceae family.  Several heads are alternately arranged along the thick, hairy stem.  The leaves of the Compass Plant are most unusual as they are aligned vertically on the stem.  The name ‘Compass Plant’ comes from the fact that the basal leaves on the plant tend to align their edges or margins north and south.

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Like other members in the Silphium genus, the ray flowers on the head, or capitulum inflorescence are yellow with darker yellow disk flowers in the center of the head. Many different kinds of pollinators visit the Compass Plant throughout the growing season.

“Long-tongued bees are the primary pollinators of the flowers, including bumblebees, Miner bees, large Leaf-Cutting bees, and others. Short-tongued Halictine bees and Syrphid flies also visit the flowers, but they are less effective at pollination. Occasionally, Sulfur butterflies and Monarchs may visit the flowers for nectar. Several species of insects are specialist feeders of Compass Plant. This includes the uncommon Okanagana balli (Prairie Cicada), whose grubs feed on the large taproot, while a Rynchites sp. (Silphium Beetle) and its larvae feed on the flower heads and stems. The larvae of Antistrophus rufus and Antistrophus minor (Gall Wasp spp.) feed within the stems, forming galls that are not visible from the outside. Nonetheless, they attract the hyperparasitic wasp Eurytoma lutea, whose larvae feed on these gall formers. Similarly, the larvae of Mordellistena aethiops (Tumbling Flower Beetle sp.) feed within the stems, while the adults may eat the flowers. The oligolectic aphid Iowana frisoni sucks the juices from the flowering stems.” –http://www.illinoiswildflowers.info/