COMPOSITAE 



195 



1. A. azureus. 



2. A. cordif alius. 



3. A. Drummondii. 



4. A. aagittifolius. 



A. Novae- Angliae. 

 A. oblongifoHus. 



A. laevis. 

 A. concinnus. 



9. A. sericeus. 



10. A. exiguus. 



Lower leaves cordate, petioled. 

 Leaves entire. 

 Leaves serrate. 

 Heads 2''-3" high. 

 Heads Z"-b" high. 

 Stems densely finely canescent. 

 Stems glabrous or nearly so. 

 Stem leaves cordate-clasping. 

 Stems rough -hairy. 

 Plants 3°-8° high. 

 Plants 2° or less high. 

 Stems glabrous. 

 Leaves oblong lanceolate to ovate. 

 Leaves linear-lanceolate. 

 Stem leaves not cordate or cordate clasping. 

 Leaves silvery on both sides. 

 Leaves not silvery. 

 Stem leaves linear. 

 Stems rough-pubescent. 

 Stems glabrous to villous. 

 Heads 3"-4" broad. 

 Heads i"-&' broad. 

 Stem leaves lanceolate. 



Heads not one-sided on the branches. 

 Stems glabrous or nearly so. 

 Kays violet. 

 Rays white. 



Eays 3"-4" long. 

 Eays 2"-3" long. 

 Stems finely canescent. 

 Heads strongly one sided on the branches. 



1. A. azureus Lindl. l°-3° high, rough or smooth : lower leaves ovate- 

 cordate to lanceolate, rough,' the upper linear to lanceolate : involucral 

 scales strongly green- tipped : rays 10-26, bright blue. — Not uncommon in 

 dry places throughout the southern part. September-October. 



2. A. cordifolius L. l°-4°high: lower leaves ovate-cordate, the upper 

 ovate to lanceolate : heads 2"-3" high : bracts ohtusish to acute : rays 

 10-20, bluish. This and the next two species freely intergrade with us. 

 — Abundant in woods. September-October. 



3. A. Drummondii Lindl. Distinguished from the last chiefly by 

 being finely and densely canescent all over and having heads 3"-5" high : 

 bracts more acute. — Frequent in dry woods, especially in the southern 

 part. September-October. 



4. A. sagittifolius Willd. Like A. Drummondii, but whole plant 

 nearly glabrous and involucral scales looser. — Dry oak woods near Dod- 

 son. September-October. 



5. A. Novae-Angliae L. Stems hairy : leaves lanceolate, entire, 

 pubescent : involucral scales spreading, glandular-viscid : rays 40-50, 

 violet-purple, 6" long. — In moist grounds throughout, but uncommon. 

 August-October. 



6. A. oblongifoliua Kntt. Stems glandular-puberulent : leaves ob- 



11. A. parviceps. 



12. A. ericoides piloaus. 



13. A. saKcif alius. 



14. A. paniculatus. 



15. A. Tradescanti. 



16. A. Missouriensis. 



17. A. laieriflorus. 



