190 COMPOSITAE 



Stem leaves opposite. 18. PoLYMNiA. 



Leaves alternate. 21. Parthenium. 



Disiv flowers ripening seeds. 

 Leaves not pinnatilid. 



Pappus none or minute. 23. ECLIPTA. 



Pappus of disk flowers of 4-6 fimbriate 



scales. 32. Galinsoga. 



Leaves pinnatifid. 



Heads less than 4'^ broad. 37. Achillea. 



Heads much more than 4^^ broad. 38." Anthemis. 



Involncral bracts stronjily fimbrillate. 47. Cextaurea. 



1 . VERNONIA Schreb. Ironweed. 



Leaves alternate. Heads cj'mose-paniculate, many-flowered. Flowers 

 purple. 



Bracts of involucre -with filiform tips. 1. V. crinita. 

 Bracts of involucre not filiform-tipped. 



Leaves linear-lanceolate. 2. V. fasciculata. 

 Leaves lanceolate to ovate lanceolate. 



Leaves little pubescent beneath. 3. V. maxivia. 



Leaves strongly pubescent beneath. 4. V. interior. 



1. V. crinita Kaf. 4°-8° high, glabrate to downy : leaves lanceolate, 

 dentate to denticulate : heads 50-70- flowered. — One clump on the prairie 

 near Waldo Park, i^robably a waif. July-October. 



2. V. fasciculata Michx. 3°-7° high, pubescent or glabrate : leaves 

 linear-lanceolate, finely serrate, thick, 1,"-^' broad : heads 20-30-flow- 

 ered, 2" broad : scales acute or obtuse, appressed. — Occasional in low 

 grounds throughout, but abundant in the northeastern part. August- 

 October. 



3. V. maxima Small. 4°-10° high, pubescent or glabrate : leaves 

 lanceolate, sharply serrate, thin, broader than the last : heads like the 

 last, but scales iicute to mucrouate. — In low grounds especially along the 

 Missouri River. Possibly only a low ground form of the next. July- 

 October. 



4. V. interior .Small. Resembles number 3, but leaves usually densely 

 pubescent beneath : heads Z" broad : i n vol ucral scales appressed. — Abun- 

 dant in dry grounds throughout. June-October. Our most common 

 species. 



Var. Drummondil (Shuttlw. ) Mackenzie & Bush, n. comb. Heads 

 \"-Q" l)road. — Common in dry grounds especially in the southern part. 

 { V. J)rt(inmo)iili Shuttlw.) 



Var. Baldwhiii (Torr. ) Mackenzie & Bush, n. comb. Heads 3'^ 

 broad : scales of involucre spreading or recurved. — Dry woods at Swope 

 Park. Not common. {]\ Btthhvinii Ton.) 



2. ELEPHANTOPUS L. 

 Heads 2-5-flowered, several togetlier forming bracted glomerules. 

 Pappus of a few awu-like bristles. 



