6G0 



WEED FLORA OF IOWA 

 FIELD 8.* 



Weed 



Date 



*In sheltered place on the south side of the railroad grade. Weeds were 

 not all counted on April 27th, but there were hundreds of small ragweeds and 

 smartweeds, and probably more than a thousand green foxtail plants. 



+ + Winter annual. 



+ Perennial. 



These tables reveal some interesting facts. The first weeds to 

 appear in March were the winter annuals, like peppergrass and 

 shepherd's purse, certain perennial weeds, and in one case horse- 

 weed {Erigeron canadensis) in a timothy meadow. Two weeks 

 later smartweed {Polygonum) was abundant. Spurge {Euphor- 

 bia), an annual, was abundant in the latter part of April and 

 early May. Foxtails in some cases surpassed all other weeds in 

 abundance early in May. The smartweeds {Polygonum) and 

 spurges increased enormously. These weeds were entirely removed 

 from the plots. Fall plowing and clean cultivation certainly in- 

 dicate a smaller number of weeds. 



Long, who measured off a square yard of ground in* Great 

 Britain, roughly grouping its plant life therein into species, found 

 on this square yard 1,050 seedlings or 5,082,000 per acre. There 

 were 654 buttercup seedlings, 107 of annual meadow grass, 60 of 

 dock, 26 of goosefoot, 25 of groundsel, 15 of shepherd's purse, 14 of 



*Trans. of Highland Agri. Soc. Scotland V. 23: 52. 



