246 IOWA ACADEMY OF SCIENCES. 



HiERACiUM L. Hawk-weed. 



518. II. nn/adoitse Michx. Woods west of Estherville; 



infrequent. 

 Nab ALUS Cass. 



519. N. alhns (L.) Hook. (Pre)i(uifhes alba L.) Rare; 



woods alont; west fork of Des Moines. 



520. X. asper (Michx.) Torr. and (iray. {Frenanthes 



aspera Michx.) Frequent on prairies. 



521. N. rarcniosKS (Michx.) I) C. ryenanilies racemosa 



Michx. Frequent on prairies. 



AMBROSIACE^. 

 IVA L. 



522. 7. xanthiifolia (Fresen.) Nutt. A troublesome 



weed in rich ground; introduced from the 

 Northwest about 1870. 

 Ambrosia L. 



528. A. trifiila L. Great Ragweed. Very common; 

 woods and waste places. 



524. A. artemisia'folia L. Common Ragweed. A very 



common and troublesome weed. 

 Xanthium L. 



525. X. raiHtdeiise Mill. Cockle-bur. Common along 



streams and introduced into cultivated fields. 



CARDUACE^. 



Vernonia Schreb. 



526. V. fascicnlata Michx. Iron-weed. Common in 



low ground. 



EUPATORIUM L. 



527. K. jnirpiircam L. Trumpet-weed. Frequent in 



woods along west fork of Des Moines. 



528. E. afjeratoides L. f. White Snakeroot. Yery 



common in woods. 



529. E. perfoliatum L. Boneset. Common; low places, 



woods and prairies. 



KUHNIA L. 



530. K. eiijiatorioides L. Dry knolls and river banks; 



common. 



