WEED MIGRATION 



721 



Artemisia biennis. Wormwood. 

 Erechtites hieracifolia, Fireweed. 

 Arctium lappa, Burdock. 



ClRSIUM LANCEOLATUM, Bull thistle. 



C. arvense, Canada thistle. 

 C. canescens, Woolly thistle. 

 Cichorium intybus, Chicory. 

 Leontodon autumnalis, Hawkbit. 

 Taraxacum officinale, Dandelion. 

 T. erythrospermum, Red-seeded dandelion. 

 Sonchus asper, Spiny-leaved sow thistle. 

 Lactuca scariola, Prickly lettuce. 



L. SCARIOLA VAR. INTEGRATA. 



Lydgodesmia juncea, Lygodesmia. 

 Solidago canadensis, Goldenrod. 



Fig. 54 8. 



46 



Narrow Sneezeweed (Helenium tenuifolium) . General aspect of plant 

 and a single head enlarged. 

 (After Chesnut, U. S. Dept. Agr.) 



