WEED MIGRATION 743 



Senecio palustris (ragwort). 



Stachys pahtstris (woundwort) (As.). 



Taraxacum officinale (dandelion). This species occurs every- 

 where in the United States and Europe, even on the highest moun- 

 tains. 



Fig. 560. Dandelion (Taraxacum officinale). Common in the northern hemis- 

 phere, across the continent. 



INTRODUCTION OF SOME WEEDS INTO THE UNITED 

 STATES AND INTO IOWA. 



CHENOPODIACEAE, GOOSEFOOT FAMILY. 



Russian Thistle (Salsola kali var. tenuifolia). 



This plant has long been known as a troublesome weed. Henfrey, 

 in his work, "The Vegetation of Europe, its Condition and Causes," 

 published in 1852, notes its abundance in Russia, east of the Volga. 



