626 MINNESOTA BOTANICAL STUDIES. 



8. Horseweed (Leptilon canadense). On the higher ridges, 

 where common rush grew in '98. 



II. Aquatics, marsh plants and cryptogams which were still 

 struggling along in a few spots. July of this year, the most im- 

 portant month of growth for annual and perennial herbs in this 

 region was unusually dry, showing a monthly deficiency in 

 precipitation of 1.75 inches.* This condition was unfavorable 

 for aquatics and marsh plants, but favorable for such plants as 

 horseweeds and common ragweeds. 



1. Wild rice (Zizania aquaticd). 



2. Water plantain (Altsma -plantago-aqiiatica). 



3. Common rush {Juncus cffusns}. 



4. Broad-leaved cattail (Typha lalifolia). 



5. Tuberous white water lily (Castalia tuberosa). Identi- 

 fied from leaves only. 



6. Large yellow pondlily {Nymphea advena}. Leaves 

 only, a flower bud found an inch deep in wet soil. 



7 . Horsetails ; mosses, amongst them Funaria hygrometrica ; 

 liverworts, with Marchantia polymorpha fairly common. 



III. Plants of which only a few scattered specimens were 

 found. 



1. Slender nettle (Urtica gracilis], 



2. Swamp milkweed (Ascleptas incarnatd). 



3. Smooth bur-marigold (Bidens lavis}. 



4. Marsh skullcap (Scutettaria galericulata). 



5. Blue vervain ( Verbena hastatd]. 



6. White vervain ( Verbena urticifolid). 

 7- Beggarticks (Bidens frondosa}. 



8. Aster-like boltonia (Boltonia asteroides}. 



9. Rough cinquefoil (Potentilla monspeliensis). 



10. Great ragweed (Ambrosia trifida}. 



11. American cocklebur (Xanthium canadense]. 



12. Prickly lettuce (Lactuca scariola). 



13. Lactuca sp. 



14. Heart-leaved willow (Salix cordata], 



15. Salix sp. 



16. Cottonwood (Popuhis deltoides], 



17. American aspen (Populus tremuloides}. 



18. Sullivant's milkweed (Asclepias sullivantii}. Identified 

 from leaves only. 



*The rainfall data of this paper are taken from the Monthly Meteorological 

 Summary of the United States Weather Bureau for St. Paul, Minn. 



