Etymology: Parthenium: Greek parthenos for "virgin" referring to infertile disk flowers
Plants: robust, erect, perennial, 20"-40" tall, aromatic forb usually with no branches
Leaves: alternate, large, toothed; lower on long stalks, upper smaller and stalkless to clasping
Flowers: head white, 1/4" wide with a few rays and a prominent disk; inflorescence of many heads in dense, flat-topped clusters; blooms July-Sept.
Fruits: black, dry seed without a fluffy pappus
Habitat: full sun; dry to moist; prairies, woods; in sandy, loamy soil
Conservation Status: Threatened

Flora of North America: Flora of North America Floristic Rating: Coefficient of Conservatism = 8 WIS DNR-Bureau of Endangered Resources: Detailed information on Wisconsin listed species including state and federal status, photos, etc. 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 Minnesota Dept. of Natural Resources: Rare Species Guide; description, conservation, photos, maps, etc. 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"