Silphium pinnatifidum

Common Name: Tansy Rosinweed 
Type: Herbaceous perennial
Family: Asteraceae
Native Range: Southeastern and central 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


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 herbaceous perennial native to prairies, glades, fens, railroad right-of-ways, and other exposed habitats in the Midwest and portions of the southern United States. 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.

Variety pinnatifidum is distinguished from the species by having pinnately lobed leaves.

The genus name Silphium comes from the Greek name silphion, used to refer to a resin-bearing plant from northern Africa.

The specific epithet terebinthinaceum comes from Greek and means "like turpentine" in reference to the aromatic resin produced in the stem. The infraspecific epithet pinnatifidum means "deeply divided" in reference to the pinnately lobed leaves of this variety.

The common name rosinweed refers to a resin produced by the plant during flowering.


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 stems often lean.


Good height for the rear of a border. Also excellent for naturalizing in prairies, cottage gardens, wildflower gardens or native plant gardens.