Eupatorum

(from an ancient personal name). Compositae. More than 400 species, mostly of warm or tropical countries, herbs or shrubs. Heads discoid (rayless), the florets 3 to many, perfect: involucre cylindrical, bell-shaped or hemispherical, the imbricated bracts in 2 or more series: receptacle flat or conical, naked : Corolla regular, 5-toothed, slender-tubed: alkenes 5-angled, truncate: pappus a single row of hair-like, scabrous bristles: perennials.