26o UNIVERSITY OF MISSOURI STUDIES [^102 



21. Leaves glabrous, or nearly SO, on both sides; pappus 

 purplish; heads large; bracts obtuse. V. Michiga- 

 nensis Daniels. Nov. .spec. Michigan ironwekd. 



Plant 1 3^-2 metres in height; stems glabrate or slightly 

 pubescent above; leaves elliptic-lanceolate, serrate, 

 glabrate; cymes medium to ample; heads large, 8-io 

 mm. high; bracts oblong, obtuse to subacute, ap- 

 pressed; pappus red-purple. Common in the Grand 

 river valley in Central Michigan. 

 22. Leaves glabrous, or nearly so, on both sides; pappus 

 purplish; heads under medium ; bracts obtuse, loosely 

 spreading at maturity. V. gig'antea (Walt.) Tre' 

 lease [F. a//z's.«';»a Nutt. in part]. Giant ironweed 

 South Carolina to Florida and Alabama. 



22a. As above, but heads slightly larger; leaves tomentose 

 beneath. V. gigantea praealta (Michx.) Daniels 

 \_V. pj'aealta (L..?) Michx.]. MiCHAUx's ironweed. 

 South Carolina to Louisiana. 



23. Leaves glabrous, or nearly so, on both sides; pappus 

 purplish; bracts obtuse, appressed at maturity; heads 

 6 to 7^^ mm. high; corymbs ample. V. altissima 

 Nutt. \^V. gigantea (Walt.) Britton, in part: V. max- 

 ima Small]. Tall ironweed. 



23a. As above, but the peduncles and under surfaces of the 

 leaves pubescent. V. altissima pubescens (Mor- 

 ris) Daniels [ f^. maxima pubescens Morris]. Hairy 

 tall ironweed. West Virginia to Alabama. 



24. Leaves glabrous, or nearly so, on both sides; pappus 

 purplish; bracts obtuse, appressed at maturity; heads 

 under 6 mm. high; corymbs few-branched. V. oli- 

 gantha Greene. Few-flowered ironweed. Flor- 

 ida. 



25. Leaves glabrous, or nearly so, on both sides; pappus 

 purplish; bracts acuminate. V. OValifolia T. & G. 

 Oval-leaved ironweed. Georgia to Florida. 



§■ Stenophyllae. Leaves linear, or even filiform. 



a. Fasciculatae. Leaves smooth above, bracts obtuse, or 

 merely acutish. 



26. Leaves pubescent beneath; involucre campanulate, cil- 

 iate; pappus purplish. V. Guadalupensis Heller. 

 Guadalupe ironweed. Texas. 



27. Leaves pubescent beneath; involucre liemispheric, 

 densely arachnoid ciliate; pappus purple-tawny. 



V. Reverchonii Gleason. Reverchon's ironweed. 

 Texas. 



28. Leaves pubescent beneath; pappus buff. V. chryso- 

 pappa Daniels. Buff-pappose ironweed. 



