basal-leaved rosinweed, prairie rosinweed, prairie-dock
[Silphium rumicifolium Small]
Etymology: Silphium: old Greek generic name referring to resinous juice
Plants: erect, perennial, 2'-10' tall forb; stems mostly leafless and smooth
Leaves: all large, basal, long stalked, rough, un-lobed but toothed, with a wide, heart-shaped base
Flowers: head 2"- 3 1/2" wide with about 13-21 yellow rays 3/4"-1" long, disk 1/2"- 1 1/2" wide; inflorescence of several to many heads in an open, branched cluster; blooms July-Sept.
Habitat: full sun; moderate moisture to wet; prairies; in sandy, loamy soil
Conservation Status: Native
Flora of North America: Flora of North America Floristic Rating: Coefficient of Conservatism = 7, Wetland Indicator = FACU Atlas of the Wisconsin Prairie and Savanna Flora: by T.S. Cochrane & H.H. Iltis: habitat, distribution infomation / flowering and fruiting times USDA Plants Database: Federal Distribution and detailed information including photos USGS - Northern Prairie Wildlife Research Center: Wetland Plants and Plant Communities of Minnesota and Wisconsin Dan Tenaglia's The Missouri Flora: Fabulous photographs; detailed descriptions; color and leave arrangement key. Illinois Wildflowers: Wonderful photographs; detailed descriptions; color and leaf arrangement key Southwest School of Botanical Medicine: Britton & Brown Illustrated Flora - 2nd Edition (1913) "An Illustrated Flora of the Northern United States and Canada"