172 COMPOSITE. 



EUPATORIUM.— Thokoughwort. 



Character of the Genus. — Heads few- or many flowered ; flowers all tu- 

 bular, perfect. Involucre cylindrical or campanulate, the scales imbri- 

 cated in two or more series, or sometimes nearly equal in a single series. 

 Keceptacle flat or slightly convex, naked. Corolla 5-toothed. Anthers 

 included. Branches of the style mostly exserted. Achenia 5-angled. 

 Pappus a single series of capillary bristles, scabous or minutely serrulate. 



Perennial herbs, with opposite, rarely alternate or whorled leaves. 

 Heads generally corymbose ; flowers purple, blue, or white. Leaves and 

 flowers often resinous-dotted. 



Eupatorium perfoliatum Linne. — Thoroughwort, Bone-set. 



Description. — Heads 10- to 15-flowered, white, in a large compound 

 corymb. Scales of the involucre 12 to 15, very pubescent, glandular, im- 

 bricated ; the inner ones linear-lanceolate, with scarious tips. Achenia 

 glabrous or minutely glandialar. 



Stem stout, 2 to 4 feet high, very pubescent or hirsute, corymbosely 

 branched above. Leaves lanceolate, opposite, united at the base about the 

 stem so as to appear perfoliate, tapering to a slender point, obtusely ser- 

 rate, veiny, wrinkled, the lower surface tomentose-pubescent and resinous- 

 dotted. It flowers late in summer. 



Habitat. — In low grounds, United States and Canada ; everywhere 

 common. 



Eupatorium purpureum Linne. — Joe-Pye Weed, Trumpet-Weed, 

 Gravel-Root. 



Description. — Heads cylindrical, 5- to 15-flowered, purple, in a dense 

 compound corymb. Scales of the involucre numerous, purplish, obtuse, 

 slightly s'triate, closely imbricated in several series, the outer short. 

 Achenia glabrous and more or less glandular. 



Stem stout, 3 to 7 or more feet high, simple, pubescent or glabrous. 

 Leaves 3 to 6 in a whorl, oblong-ovate or lanceolate, pointed, veiny, 

 scabrous or glabrous above, somewhat pubescent beneath, serrate, resin- 

 ous-dotted. It flowers from July forward. 



Habitat. — In low grounds, United States and Canada ; everywhere 

 common. 



These two species fairly represent the medicinal activity of the genus ; 

 many other species possess similar properties. 



Parts Used. — Of E. perfoliatum, the leaves — United States Pharmaco- 

 poeia ; of E. purpureum, the root — not official. 



Constituents. — The official species contains a large percentage of a pecu- 

 liar bitter extractive, to which its therapeutic effects are attributed, but 

 whose chemical character is as yet undetermined. The constituents of E. 

 purpureum have not been ascertained. 



