prairie dock

(Silphium terebinthinaceum var. terebinthinaceum)

Conservation Status
prairie dock
  IUCN Red List

not listed


NNR - Unranked


not listed

Wetland Indicator Status

FAC - Facultative

  Northcentral & Northeast

FAC - Facultative


Prairie dock, also called prairie rosinweed, is a 40 to 98 tall, erect, long-lived, perennial forb that rises on a bassal rosette and usually a single stem from a woody taproot. The taproot may extend up to 12 deep.

The stem is erect, round, hairless, and usually branched. It is sometimes slightly covered with a whitish, waxy coating (glaucous).

A basal rosette of large, thick, leathery basal leaves appears early in the season. Later, a single flowering stalk bolts from the center of the rosette and reaches full height in just a few days.

Basal leaves are on long leaf stalks and may be triangular, lance-shaped, or egg-shaped. The blades are unlobed, 6 to 20 long, and up to 12 wide. They are usually broadly heart shaped at the base and rounded, angled, or tapered to a point at the tip. The upper surface is hairless and shiny when young, moderately covered with spreading hairs, dull, and rough to the touch when mature. The lower surface is hairy, especially along the midrib. The margins may be coarsely toothed or untoothed. Sometimes there are one or more similar long-stalked leaves attached to the stem near the base.

The flowering stems are nearly naked, with usually a few much-reduced, bract-like leaves. Stem leaves are alternate, egg-shaped, stalkless, and to 1¼ long. They clasp the stem at the base but do not wrap completely around the stem. The margins are untoothed.

The inflorescence is an open, branched cluster (panicle) of one to several flower heads at the end of the stem and branches.

Each flower head is 2 to 3½ wide with disk ½ to 1½ wide. There is a whorl of 23 to 33 bracts (involucre) in 2 or 3 overlapping series at the base of the flower head. The involucre is ½ to 1 in diameter. The outer bracts are short, broadly elliptic, and tightly appressed. The inner bracts are longer, oblong-elliptic, loose, and usually ascending at the tip. The outer surface is hairless, and sometimes there is a dense fringe of minute hairs along the margin.

There are 17 to 29 yellow ray florets and 120 to 140 yellow disk florets. The ray florets are ¾ to 1¼ long. The disk florets are sterile. The flower heads are not fragrant.

The fruit of the ray floret is a dry cypsela with no fluffy tuft of hairs attached. The cypsela is black, egg-shaped, strongly flattened, winged, ¼ to ½ long, and to wide.




40 to 98


Flower Color


Yellow ray florets, yellow disk florets


Similar Species


Moderate moisture to wet. Prairies. Full sun.




July to September


Pests and Diseases






Distribution Map



7, 24, 29, 30.

Prairie dock has not been recorded in the state by the Minnesota DNR or collected by a Minnesota herbarium. Its known range extends no farther west than central Wisconsin and extreme eastern Iowa. In 2015 there were just three records of it in Minnesota. Since then its range appears to be expanding northward.




Native to northeastern, north-central, and southeastern United States, including Iowa and Wisconsin, and to Ontario, Canada. Adventive.




Rare in Minnesota.

  Kingdom Plantae (green algae and land plants)  
  Subkingdom Viridiplantae (green plants)  
  Infrakingdom Streptophyta (land plants and green algae)  
  Superdivision Embryophyta (land plants)  
  Division Tracheophyta (vascular plants)  
  Subdivision Spermatophytina (seed plants)  
  Class Magnoliopsida (flowering plants)  
  Superorder Asteranae  


Asterales (sunflowers, bellflowers, fanflowers, and allies)  


Asteraceae (sunflowers, daisies, asters, and allies)  
  Subfamily Asteroideae  
  Supertribe Helianthodae  
  Tribe Heliantheae (sunflowers and allies)  
  Subtribe Engelmanniinae  
  Genus Silphium (rosinweeds)  
  Species Silphium terebinthinaceum (prairie dock)  

Subordinate Taxa






Silphium rumicifolium

Silphium terebinthinaceum var. luciae-brauniae


Common Names


basal-leaf rosinweed

basal-leaved rosinweed


prairie dock


prairie rosinweed












Modified leaf at the base of a flower stalk, flower cluster, or inflorescence.



Describing a leaf that wholly or partly surrounds the stem but does not fuse at the base.



A dry, one-chambered, single-seeded fruit, formed from a single carpel, with the seed attached to the membranous outer layer (wall) only by the seed stalk; the wall, formed from the wall of the inferior ovary and also from other tissues derived from the receptacle or hypanthium, does not split open at maturity, but relies on decay or predation to release the contents.



Pale green or bluish gray due to a whitish, powdery or waxy film, as on a plum or a grape.



A pyramidal inflorescence with a main stem and branches. Flowers on the lower, longer branches mature earlier than those on the shorter, upper ones.



A thin, flat, membranous, usually transparent appendage on the margin of a structure.

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Dave Jungst


Only a few scattered plants found in the upland on the east end of the SNA in remnant native prairie. One plant was about 7 feet tall.

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Flower Head

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Basal Leaves

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Stem Leaves

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  Silphium terebinthinaceum PRAIRIE DOCK
Frank Mayfield
  Silphium terebinthinaceum PRAIRIE DOCK  



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Other Videos
Larry Henry

Published on Aug 19, 2013

RAIN, much more than normal in the last four years, has created ideal growing conditions for most Prairie Species.. The best Prairies in Ohio are in Adams County, South Central part of the state. The flower stalks are over 7ft. tall in some locations.




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  Dave Jungst

Location: Verlyn Marth SNA, section 6, Rendsville Township, Stevens County, MN.

Only a few scattered plants found in the upland on the east end of the SNA in remnant native prairie. One plant was about 7 feet tall.

prairie dock  
  Paul Schatz

Location: Mississippi Market on west 7th, St Paul Mn. Edge of parking lot







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