14 
Table 10. Frequency, canopy cover, and composition values for noxious weeds regulated by State law within 
the study region. 






Percent Relative Percent 
Percent canopy Relative canopy relative Importance 
Species and year frequency cover frequency cover composition value 
Bull thistle@ 
1977 - — — _ — -- 
1978 ~ ~ — = _ — 
1979 0.1 'D a T T T 
Canada thistle 
1977 7.0 0.5 1.6 0.4 0.1 2.1 
1978 12.6 0.5 2.9 0.5 0.1 3.5 
1979 13.0 0.6 3.3 0.8 0.2 4.3 
Field bindweed 
1977 12.4 1,2 2.9 1. 0.3 4.3 
1978 12.4 1.0 2.9 1.1 0.2 4.2 
1979 9.6 0.9 2.5 1.2 0,3 4.0 
Leafy spurge 
1977 0.2 T T T 5 T 
1978 0.9 0.1 0.2 0.1 T 0.3 
1979 0.5 u 0.1 T T 0.1 
Plumeless thistle 
1977 0.2 T T T © T 
1978 0.3 T 0.1 T T 0.1 
1979 0.2 T 0.1 oD T 0.1 
Quackgrass 
1977 28.1 11.4 6.6 10,2 11.7 28.5 
1978 41.6 11.2 9.7 12.1 17.7 39.5 
1979 38.0 9.3 9,7 12.0 18.3 40.0 
Sow thistle 
1977 5.7 0.5 1.3 0.4 0.1 1.8 
1978 8.3 0.9 1.9 1.0 0.2 3.1 
1979 6.5 0.7 1.7 0.9 0.2 2.8 
Wormwood 
1977 0.5 T 0,1 ih I 0.1 
1978 1.5 0.1 0.3 0.1 T 0.4 
1979 2.2 0.1 0.6 0.1 T 0.7 


@Scientific names appear in Table A-3, 
Table 11. Frequency, canopy cover, and composition values for noxious weeds covered by law with regulation by 
States as averaged for 1977-79. 





Percent Relative Percent 
Percent canopy Relative canopy species Importance 
State frequency coverage frequency cover composition value 
Minnesota 7A 2.3 Tad 2.5 0.6 10.3 
Montana 5.7 1.6 5.5 1.7 ().4 7.6 
North Dakota 7.8 2.4 7.4 2.6 0.6 10.6 
South Dakota 16.4 12.9 15.8 13.9 16.5 46.2 
South Dakota! 7.4 2.3 7.1 1 0.5 10.2 



aValues with quackgrass included. 
bValues with quackgrass excluded. 

