Silphium terebinthinaceum Jacq.
Common Name: PRAIRIE-DOCK
Coefficient of Conservatism: 6
Coefficient of Wetness: 0
Wetness Index: FAC
Physiognomy: Nt P-Forb

Silphium terebinthinaceum head B. S. Walters head

This species does not range as far west into the prairies as the others, but is the most common in southern Michigan, especially in calcareous places; prairies and similar grassy habitats (even conspicuous along roadsides), fens, railroad embankments.

The very large, vertical leaves (blade up to 3 dm broad on long petioles) make this a plant recognizable from a distance even without the tall (at least to 3.5 m) stem with large heads. The large woody taproot is likewise impressive.

A Menominee Co. collection (D. Henson 1573) found in a mixed colony of this species and S. laciniatum has leaves and phyllaries intermediate, and is presumably a hybrid.

Locations

Bay County
Berrien County
Branch County
Calhoun County
Cass County
Delta County
Hillsdale County
Ionia County
Jackson County
Kalamazoo County
Kent County
Lenawee County
Livingston County
Macomb County
Menominee County
Monroe County
Oakland County
St. Joseph County
Tuscola County
Washtenaw County
Wayne County

Citation:

MICHIGAN FLORA ONLINE. A. A. Reznicek, E. G. Voss, & B. S. Walters. February 2011. University of Michigan. Web. December 14, 2017. http://michiganflora.net/species.aspx?id=448.