Silphium terebinthinaceum L. - Prairie Dock


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Silphium terebinthinaceum - (image 1 of 7)



Family: Asteraceae


Prairies. Marl flats.


In prairies the associates are similar to those of S. laciniatum. In marl flats with Cladium mariscoides, Deschampsia caespitosa glauca, Eleocharis rostellata, Juncus brachycephalus, Lobelia kalmii, Parnassia glauca, Potentilla fruiticosa, Scleria verticillata, Solidago ohioensis, Solidago patula, Tofieldia glutinosa, Tricglochin palustris.


Southern Ontario and OH west to MN, south to GA and MS.


Coarse, taprooted perennial, to 12' high. Leaves almost all basal, very large, mostly deltoid-ovate or ovate-oblong, sharply toothed, to 12" long; cauline leaves, if present, much reduced. Stems glabrous or glabrate. Heads several to numerous in an open-corymbiform inflorescence, relatively large; rays yellow, 13-21; disk to 3.5 cm wide; involucral bracts glabrous, strongly imbricate, the outer broadly elliptic, the inner elongate, more oblong, loose and broad-tipped. Fruit an achene.


Flowers late June to late September

Wetland indicator: Facultative Upland

Will bloom 2 or 3 years after planting from seed.


Gleason, Henry A. and A. Cronquist. 1991. Manual of Vascular Plants of Northeastern United States and Adjacent Canada. Second Ed.
The New York Botanical Garden. Bronx, NY


Swink, F. and G. Wilhelm. 1994. Plants of the Chicago Region.
Indiana Academy of Science. The Morton Arboretum. Lisle, Illinois.




 Michael Hough 2005