190 COMPOSITAE 



Stem leaves opposite. 18. POLYMNIA. 



Leaves alternate. 21. PARTHENIUM. 



Disk flowers ripening seeds. 

 Leaves not pinnatifid. 



Pappus none or minute. 23. ECLIPTA. 



Pappus of disk flowers of 4-6 fimbriate 



scales. 32. GALINSOGA. 



Leaves pinnatifid. 



Heads less than 4 XX broad. 37. ACHILLEA. 



Heads much more than 4 XX broad. 38.^ANTHEMis. 



Involucral bracts strongly fimbrillate. 47. CENTAUREA. 



1 . VERNONIA Schreb. IRON WEED. 



Leaves alternate. Heads cymose-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. maxima. 



Leaves strongly pubescent beneath. 4. V. interior. 



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

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

 near Waldo Park. Probably a waif. July-October. 



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

 linear-lanceolate, finely serrate, thick, 3 XX -8 XX broad : heads 20-30-flow- 

 ered, 2 XX 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 acute to mucronate. 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 3 // broad : involucral scales appressed. Abun- 

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

 species. 



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

 4 XX -6 XX broad. Common in dry grounds especially in the southern part. 

 ( V. Drummondi Shuttlw. ) 



Var. Baldwinii (Torr. ) Mackenzie & Bush, n. comb. Heads 3 X/ 

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

 Park. Not common. ( V. Baldwinii Torr.) 



2. ELEPHANTOPUS L. 



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

 Pappus of a few awn-like bristles. 



