Table 8. Continued. 
13 













Percent Relative Percent 
Percent canopy Relative canopy species Importance 
Species and year (N = 17) frequency cover frequency cover composition value 
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 
Western ragweed 
1977 9.5 0.7 2.2 0.6 0.3 
1978 3.8 0.2 0.9 0.2 T 
1979 3.5 0.1 0.9 0.1 0,1 
Wild buckwheat 
1977 39.2 5.3 9.2 4,7 1.5 15.4 
1978 12.5 0.3 2.9 0.3 0.2 3.4 
1979 23.8 0.6 6.1 0.8 0.3 Tae 
Wild oat 
1977 2.1 T 0.5 T T 0.5 
1978 0.7 r 0.2 z E 0.2 
1979 0.4 T 0.1 T T 0.1 
Yellow foxtail 
1977 11.4 1.5 2.7 1.3 1.9 3.9 
1978 4.0 0.6 0.9 0.6 0.9 2.4 
1979 3,7 0.2 0.9 0.3 0.2 1.4 



Dakota during 1978 (Table 12), At present, the primary 
target species on public lands are leafy spurge, Canada 
thistle, wormwood, and sow thistle, all obvious weed 
species. The primary target species of problem weeds on 
private cropland are wild oat, quackgrass, yellow foxtail, 
Canada thistle, and field bindweed. Quackgrass is sup- 
pressed most of the time with proper tillage management, 
the others more by herbicides. 
Vegetative Characteristics of Species Within Stands 
but not Within Quadrats 
Of the 159 plant species found in 321 SNC stands, 44 
species occurred within stands but did not occur within 
sample quadrats (Table 13), The number of species repre- 
sented in each category of vegetative characteristic were 
life-form — 34 forbs, 7 grasses, 1 tree, 1 shrub, and | succu- 
lent; growth habit — 28 perennials, 11 annuals, and 5 bi- 
ennials; and origin — 28 natives and 16 introduced species. 
All 44 species occurred as trace (< 1%) components of the 
SNC stands and most of the species were represented by a 
single specimen. 
Vegetative Characteristics of Disturbed Sites 
Within Stands 
Two kinds of disturbed areas were present in SNC 
stands, areas of exposed earth on mounds made by pocket 
gophers (Geomys bursarius and Thomomys talpoides), 
and badgers (Taxidea taxus), and areas originally left 
unsown because of skips made with seed drilling or 
broadcasting equipment. 
Vegetation associated with earth mounds. —Twenty- 
five species of plants occurred on earth mounds made by 
Table 9. Noxious weeds regulated by State law in the 
glaciated prairie pothole region, 

Covered by law with regulation in 
North = South 
Noxious weeds Dakota Dakota Minnesota Montana 
(N = 15) (N = 9) (N = 8) (N =9) (N =5) 



Bull thistle@ X 
Canada thistle xX xX X X 
Field bindweed xX X Xx X 
Hoary cress Xx X xX 
Horse nettle x 
Leafy spurge X X X X 
Marijuana Xx Xx 
Musk thistle X xX 
Perennial sow thistle xX Xx xX 
Plumeless thistle X 
Poison ivy x 
Quackgrass X 
Russian knapweed xX xX X 
Sow thistle X X x 
Wormwood X 

“Scientific names appear in Table A-3. 
