rENTANDRiA DIGYNIA. 343 



Jlaot tuberons, prpemorse. Stem 3 — 4 feet high, glabrous, hollow 

 "in the centre, small. LtcCtes 12-- 18 inches long;, 1 — H wide, subu- 

 late, acute, concave, not channelled, bordered with lonpj cilia wliich 

 resemble spines ; stem leaves sessile, not diminished at base, cm- 



bracing the stem. Involucrum many leaved, frequently not longer 

 than the head ; leaves rigid, ovate, acuminate, mucronate, sometimes 

 toothed. Heads longer than in tlie preceding species. Covulla whit»*y 

 chaffy, generally undivided. 



Grows in flat, damp, poor soils; 



Flowers June — July, Button Snake-root. 



■ The root of tins plant is oT a pungent bitter and aromatic taste. 

 When chewed it very sensibly excites a flow of saliva. A decoction 

 of the root is diaphoretic and expectorant, and sometimes proves 

 emetic. It is preferred by some physicians to the scncka snake-root, 



which it much resembles in its eflects. 



2, ViRGiifliANrM. Persoon. 



E. foliis longo-lanceo- I Leaves long lanceo- 

 latis, serratis ; involucre | late, serrate ; involucrum^ 

 capitulis multo longiore ; I much longer than the 

 paleis tricuspidatis. E. | heads ; chaff 3 cuspidate. 



Pursh, 1. p. 189. 



E. aquaticum, Mich. 1. p. 163. 



Boot tuberous, prsemorse. Stem herbaceous, 4—6 feet high, much 

 divided near the summit, glabrous, hollow, thickened at the joints. 

 Leaves 6 — 8 inches long, strictly lanceolate, acutely serrulate, some- 

 times dentate, tapering at each extremity but dilated at the very 

 base; the midrib very prominent; the narrow base of the leaf 3 — 4. 

 inches long. Jleadsxery numerous, forming terminal corymbs, some 

 nearly sessile. Involucrum 3 times as long as the heads, subulate, 

 l<aciniate, with a white tint on the under surface.' Corolla nearly 

 white. 



Grows in fresh marshes, and in inundated soils. Along the mar-» 

 gin of Savannah river opposite the city of Savannah very common. 



Flowers June. 



3. OvALiFOLiuiM. Mich. 

 E. foliis spathulato- 



ovatis, inciso-dentatis ; ca- 

 pitulis involucro brevio- 



Leavcs spathulate a- 

 vate, deeply toothed ; 



heads shorter than the 

 ribus ; paleis sequaliter I involucrum ; chaff equal- 

 tricuspidatis. E. | ly 3 cuspidate. E. 



Mich. 1. T). 163. 



E. virgatum, Pursh, 1. p. 189. 



Perennial. Stem 2 — 4 feet high, erect and decumbent, glabrous, 

 tellow. Leaves alternate, acutelj notched or toothed, with the mar- 



