Silphium integrifolium Michx. - Rosin Weed


|  back  | forward |

Silphium integrifolium - (image 1 of 7)



Family: Asteraceae


Prairies, calcareous fens.


In prairies with Allium cernuum, Andropogon gerardii, Aster ericoides, Baptisia leucantha, Cassia fasciculata, Coreopsis tripteris, Desmodium illinoense, Eryngium yuccifolium, Fragaria virginiana, Helianthus grosseserratus, Helianthus mollis, Monarda fistulosa, Pathenium integrifolium, Ratibida pinnata, Solidago graminifolia nuttallii, Solidago rigida, Spartina pectinata, Thalictrum dasycarpum hypoglaucum. Associate in calcareous fens include Cacalia pantaginea, Oxypolis rigidior, Parnassia glauca, Valeriana ciliata.


Southern MI to NE, south to AL, MI, and TX


Coarse, stiff, herbaceous perennial, to 5' high. Leaves opposite, scabrous below, sessile, often clasping, entire or slightly toothed, ovate or lance ovate to elliptic. Stems terete or subterete. Heads many flowered; rays yellow, mostly 16-35, 5 cm long; disk mostly 1.5-2.5 cm wide; phyllaries scabrous or pubescent, eglandular. Fruit an dark, smooth achene, resembles a large sunflower seed.


Flowers mid July to mid August

Wetland indicator: Upland

Exudes a resinous substance when cut.


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