Species Native to Missouri
Common Name: prairie dock
Type: Herbaceous perennial
Family: Asteraceae
Native Range: Central-eastern Canada to southeastern United States
Zone: 4 to 8
Height: 3.00 to 10.00 feet
Spread: 1.00 to 3.00 feet
Bloom Time: July to September
Bloom Description: Yellow
Sun: Full sun
Water: Medium
Maintenance: Low
Flower: Showy
Attracts: Birds
Tolerate: Clay Soil
Culture
Easily grown in average, medium, well-drained soils in full sun. Tolerates poor soils. Hardy in Zones 4-8.
Noteworthy Characteristics
Silphium terebinthinaceum, commonly called prairie dock, is a tall, rough, Missouri native perennial which occurs in limestone prairies and glades primarily in the northeast, central and Ozark regions of the State. From a basal clump of huge oval to heart-shaped, dark green leaves (to 2' long) rise smooth, almost leafless stems branching at the top to a height of 10' tall. Sunflower-like flowers (to 3" wide) with yellow rays and yellow center disks bloom in loose clusters on the upper parts of the plant in mid to late summer. The seeds are attractive to birds.
The genus name Silphium comes from the Greek name silphion, used to refer to a North African resin bearing plant.
The specific epithet terebinthinaceum comes from Greek and means "like turpentine" in reference to the aromatic resin produced in the stem.
Problems
No serious insect or disease problems. Taprooted, slow-to-establish plant which may not flower until the second or third year. Usually does not need support, but often leans.
Garden Uses
Good height for the rear of the border. Also excellent for naturalizing in prairies, cottage gardens, wildflower gardens or native plant gardens.