CAKDUACEAE 1165 



Stem pubescent : involucres 4 mm. high. 19. E. semiserratum. 



Involucres 5-6 mm. high, over 2 mm. thick. 20. E. altissimum. 



Lower leaf-blades decidedly broadest above the middle. 

 Involucres about 5 mm. high : cauline leaves with entire 



blades. 21. E. tortifolium. 



Involucres about 7 mm. high : cauline leaves with toothed 



blades. 22. E. citneifolium. 



Bracts of the involucre acute, acuminate or mucronate. 



Leaf-blades linear or of a linear type : involucre 6-7 mm. high. 

 Inner bracts of the involucre merely acute : leaf-blades 1- 



ribbed. 23. E. leucolepis. 



Inner bracts of the involucre awn-tipped : leaf-blades 3- 



ribbed. 24. E. Mohrii. 



Leaf-blades of an oblong or lanceolate type : involucres 8-10 



mm. high. 

 Outer bracts of the involucre subulate-lanceolate, acuminate, 



inner bracts linear, not petaloid, acuminate. 25. E. album. 



Outer bracts of the involucre linear, acute : inner bracts 



spatulate, petaloid, mucronate. 26. E. petaloidcum. 



Base of the leaf-blade broady rounded, cordate, truncate or broadly 



cuneate. 

 Leaf-blades crenate, crenate-serrate or crenate-dentate. 



Branches of the inflorescence alternate : leaf-blades coarsely 



few-toothed. 27. E. verbenaefolium. 



Branches of the inflorescence opposite : leaf-blades more finely 



and evenly toothed. 

 Leaf-blades about as broad as long, truncate or subcordate 



at the base. 28. E. rotundifolium. 



Leaf- blades manifestly longer than broad, rounded or 



broadly cuneate at the base. 

 Involucres over 4 mm. high : leaf -blades rounded at the 



base. 29. E. puhescens. 



Involucres less than 4 mm. high : leaf-blades broadly cu- 

 neate at the base. 30. E. scabridum 

 Leaf-blades sharply serrate. 31. E. sessiitfolium. 

 B. Leaf-blades connate-perfoliate or connate-clasping. 

 Leaf-blades connate-clasping. 



Involucre cylindric, about 5 mm. high ; bracts mainly linear : 



leaf-blades oblong to oblong-ovate. 32. E. Chapmanii. 



Involucre campanulate, 3.5-4 mm. high ; bracts mainly oblong : 



leaf-blades lanceolate to oblong-lanceolate. 33. E. cuneatum. 



Leaf- blades connate-perfoliate, except in E. perfoliatum truncation. 34. E. perfoliatum. 

 Leaves whorled in 3's to 6's; blades relatively broad. 



Leaf-blades rugose, manifestly pubescent : inflorescence depressed. 35. E. maculatum. 



Leaf-blades not rugose, nearly glabrous : inflorescence pyramidal. 



Leaf-blades crenate, the teeth somewhat apiculate. 36. E. trifoliatum. 



Leaf-blades sharply serrate. 37. E. purpureum. 



1. Eupatorium capillifolium (Lam.) Small. Villous to glabrate, fennel-scented. 

 Stems 1-3 m. tall, paniculately much branched : leaves very numerous, mostly alternate ; 

 blades much compound, the segments linear-filiform to filiform, acute : heads very numer- 

 ous, in panicled racemes or panicles : involucres 2-3 mm. high, 3-6-flowered ; bracts 

 lanceolate to linear-lanceolate, glabrous, acuminate to mucronate, scarious-margined : 

 corollas white : achenes 1 mm. long, glabrous. \_E. foeniculaceum Willd.] 



In old fields and dry soil, Virginia to Florida. Fall, 



2. Eupatorium compositifolium Walt. Puberulent to finely pubescent, more or 

 less viscid and aromatic. Stems 6-12 dm. tall, paniculately branched : leaves numerous ; 

 blades twice 3-7-parted on the lower part of the stem, gradually less compound above, and 

 entire near the top, the segments linear or nearly so : heads very numerous, in panicled 

 racemes or panicles : involucres 3-4 mm. high, 3-6-flowered ; bracts narrowly lanceolate, 

 mucronate, or the inner acuminate pubescent, scarious-margined : corollas white : achenes 

 1.5 mm. long, glabrous. [E. coronopifolium Willd.] 



In dry soil or open woods, North Carolina to Florida and Texas. Summer and fall. 



3. Eupatorium Eugfenei Small. Similar to E. pinnatifidum in habit, but the seg- 

 ments of the leaves commonly narrower. Heads numerous, aggregated at the ends of the 

 slender branches of the inflorescence and borne in a thyrsoid panicle : involucres 3.5 mm. 

 high ; bracts ovate to linear-spatulate, the inner mucronulate or nearly obtuse : corollas 

 white : achenes fully 1 mm. long. \_E. Smithii Greene & Mohr, not Robinson. ] 



In dry or sandy soil, Alabama and western Florida. Fall. 



4. Eupatorium pinnatifidum Ell. Finely pubescent. Stems 6-12 dm. tall, branch, 

 ing : leaves opposite or in whorls of 4 ; blades pinnately 2-3-parted, or the upper one- 

 twice pinnately parted or entire, the segments linear or nearly so : heads very numerouss 

 sometimes densely crowded : involucres about 3 mm. high, 6-9-flowered ; bracts ovate to 

 linear, prominently cuspidate : corollas white : achenes about 1 mm. long, glabrous. 



In dry grounds, North Carolina to Florida and Alabama. Summer and fall. 



5. Eupatorium pectinatum Small. Finely pubescent. Stems 1-2 m. tall, corym- 

 obsely branched above : leaves rather numerous ; blades mostly 5-15 cm. long, larger on 



