GENUS 4. 



THISTLE FAMILY 



10. Eupatorium semiserratum DC. 



Small-flowered Thoroughwort. 

 Fig. 4161. 



E. semiserratum DC. Prodr. 5: 177. 1836. 



Pubescent or puberulent, loosely branched 

 above, 2-3 high. Leaves rather thin, short- 

 petioled, oblong-lanceolate to spatulate, acute 

 or obtusish at the apex, narrowed at the base, 

 sharply serrate, at least above the middle, 

 2'-4' long, s"-i2" wide, 3-neryed, usually 

 with short branches in their axils ; inflores- 

 cence cymose-paniculate ; heads 2"-3" high, 

 about 5-flowered ; involucre campanulate, 

 its bracts linear-oblong, obtuse, canescent, 

 imbricated in 2 or 3 series, the outer shorter, 

 flowers white. 



In dry soil, Virginia to Florida, Missouri, 

 Arkansas and Texas. Aug.-Sept. 



ii. Eupatorium altissimum L. Tall 

 Thoroughwort. Fig. 4162. 



Eupatorium altissimum L. Sp. PI. 837. 1753- 



Densely and finely pubescent, corymbosely 

 much-branched above, 4-8 high. Leaves 

 lanceolate, acuminate at the apex, tapering 

 below into a short petiole, roughish, rather 

 thick, sparingly dentate above the middle, 

 or some of them entire, strongly 3-ribbed, 

 2'-$' long, s"-i2" wide ; inflorescence dense- 

 ly cymose-paniculate; heads about 5-flow- 

 ered, 3"-4" high ; involucre campanulate, 

 its bracts oblong, obtuse or truncate, densely 

 pubescent, imbricated in about 3 series, the 

 outer shorter; flowers white. 



In dry open places, Pennsylvania to North 

 Carolina, Alabama, Illinois, Minnesota, Ne- 

 braska and Texas. Sept.-Oct. 



12. Eupatorium sessilifolium L. Up- 

 land or Bastard Boneset. Fig. 4163. 



Eupatorium sessilifolium L. Sp. PI. 837. 1753. 



Glabrous throughout, or pubescent above, 

 branched near the summit, 2-6 high. Leaves 

 opposite, or the lower rarely in 3's, closely ses- 

 sile, lanceolate or ovate-lanceolate, long-acumi- 

 nate, thin, sharply serrate, 3'-6' long, i'-ll' 

 wide, inflorescence cymose-paniculate ; heads 

 4"-5" high, about 5-flowered ; involucre cam- 

 panulate, its bracts linear-oblong, imbricated in 

 about 3 series, the inner obtuse, the outer acut- 

 ish, shorter; flowers white. 



In dry woods, Vermont to Massachusetts, Penn- 

 sylvania, Georgia, Alabama and Missouri. Aug.- 

 Oct. A related plant, described under the name 

 Eupatorium sessilifdlium Brittonidnum Porter, 

 has leaves ovate or oblong-ovate, sparingly and 

 finely serrate, firm, rounded at the base, acute, the 

 upper i '-2' long, 6"-g" wide, pinnately veined, 

 dark green ; cymes dense, their branches puberulent. 



It is known only from Budd's Lake, N. J. 



