Silphium laciniatum, the compass plant, is a native perennial which occurs in prairies, wood edges and glades. It is a tall, sturdy, rough, bristly plant that grows on stiff, hairy, resinous stems to 9' tall. It features sunflower-like flowers (to 5" wide) with yellow rays and yellow center disks. Flowers bloom in loose spikes on the upper parts of the plant in summer. Very large, deeply pinnatifid (cut close to the midrib) basal leaves (to 18" long) are reminiscent of pin oak leaves. The upper leaves are smaller. Basal leaves usually orient themselves on a north-south axis so as to minimize intense overhead sun exposure, thus giving rise to the common name. Split or broken stems exude a gummy, fragrant-but-bitter resin which was used by Native Americans as a mouth-cleansing chewing gum. Many of the silphiums are commonly called rosinweed.
The genus name Silphium comes from the Greek name silphion, used to refer to a North African resin bearing plant; laciniatum means slashed or torn into narrow segments for the deeply cut leaves.
Easily grown in average, medium, well-drained soils in full sun. Tolerates poor soils.
Ther are no serious insect or disease problems. It can be slow to establish and may not flower until the second or third year.
It has good height for the rear of the border. Like other Silphiums, it's excellent for naturalizing in prairies, cottage gardens, wildflower gardens or native plant gardens.
Text Adapted from: Missouri Botanic Garden
Photo from Missouri Botanic Garden Website