Common Name: compass plant
Type: Herbaceous perennial
Native Range: Central United States
Zone: 3 to 8
Height: 5.00 to 9.00 feet
Spread: 1.50 to 3.00 feet
Bloom Time: July to September
Bloom Description: Yellow
Sun: Full sun
Easily grown in average, medium, well-drained soils in full sun. Tolerates poor soils.
Silphium laciniatum, commonly called compass plant, is a Missouri native perennial which occurs in prairies and glades throughout most of the State. A tall, sturdy, rough, bristly plant that grows on stiff, hairy, resinous stems to 9' tall. 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. 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.
Genus name comes from the Greek name silphion used for a North African resin bearing plant.
Specific epithet means slashed or torn into narrow segments for the deeply cut leaves.
No serious insect or disease problems. Slow to establish and may not flower until the second or third year.
Good height for the rear of the border. Also excellent for naturalizing in prairies, cottage gardens, wildflower gardens or native plant gardens.