[Ageratum altissimum "L., non Eupatorium altissimum L.", more]
Etymology: Eupatorium: from Greek name Mithridates Eupator, King of Pontus about 115BC who is said to have discovered an antidote to a commonly used poison in one of the species
Plants: erect, perennial, 1'-5' tall forb with 1 to 3 mostly hairless, leafy stems
Leaves: opposite, blade 1 1/2 to 5 times longer than the long stalk, bases rounded, edges coarsely toothed
Flowers: head with 12-25 white disk flowers; inflorescence 3" flat to roundish, branched clusters of many heads; blooms July-Oct.
Fruits: dry seed on fluffy pappus
Habitat: moderate moisture; woods, disturbed sites; in rocky soil
Hazardous: Careful, this plant is hazardous!
Conservation Status: Native - potentially invasive
Flora of North America: Flora of North America Floristic Rating: Coefficient of Conservatism = 1, 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 Dan Tenaglia's The Missouri Flora: Fabulous photographs; detailed descriptions; color and leave arrangement key. David G. Smith's "Delaware Wilflowers": Beautiful photographs; descriptions Illinois Wildflowers: Wonderful photographs; detailed descriptions; color and leaf arrangement key