250 
IOWA ACADEMY OF SCIENCES. 
572. B. cernua L. Smaller Bur-Marigold. Very com- 
mon in marshes or other wet places; the heads 
nodding in fruit. 
573. B. frondosa L. Spanish Needles. Common; a 
troublesome weed in low fields. 
Helenium L. 
574. H. autumnale L. Sneezeweed. Common on low 
prairies. 
Achillea L. 
575. A. millefolium L. Yarrow. Milfoil. A common 
and troublesome weed, introduced in grass 
seed, native to North America as well as Europe 
and Asia. 
Anthemis L. Mayweed. 
576. A. cotula L. {Manila cotula D C.) Frequent around 
old dwellings. 
Artemisia L. Wormwood. 
577. A. caudata Michx. Frequent on dry knolls. 
578. A. dracunculoides Pursh. Woods and prairies; fre- 
quent. 
579. A. absinthium L. Introduced into waste places 
from Europe. 
580. A. biennis Willd. Very common, especially as a 
weed in wet fields. 
581. A. gnaphalodes Nutt. (A. ludoviciana Nutt. var. 
gnaphalodes Torr. & Gray.) Woods and prairies; 
very common. 
Erechtites Raf. 
582. E. hieracifolia (L.) Raf. Fire- weed. Rare in cul- 
tivated ground; probably introduced into our 
county. 
Mesadenia Raf. 
583. M. tuber osa (Nutt.) Britton. ( Cacalia tuberosa 
Nutt.) Common on prairies. 
Senecio L. 
584. S. aureus L. Golden Ragwort. Squaw- weed. 
Frequent on prairies, usually growing in 
patches. 
