August, 1955 
Evers: Hity Prairies or ILLINOIS 387 
Table 9.—Available space per plant in the central milacre of Sampson and of Phegley 
hill prairies. 
i 
EY eee Res AVAILABLE SPACE PER PLANT 
Hivy Prairie | yy Square INCHES PLants 
Square Inches Square Centimeters 
Mampson......... 6,272.64 1,949 Sale 20.77 
iepipy......-.. 6,272.64 1,341 4.68 30.19 
three bunch-grass species are not so dif- 
ferent in size from the plants of most 
other herb species (most of them dicotyle- 
dons) as to call for separate estimations 
of available space for grasses and for other 
herbs. 
Available space per plant for Sampson 
and Phegley hill prairies is given in 
table 9. 
Numbers of Plant Species for Var- 
ious Plot Sizes.—From the species lists 
compiled for plot sizes ranging from 1/64 
milacre to 75 milacres, it was possible to 
find the average number of plant species 
in plots of several sizes and also the in- 
crease in number of species with an in- 
crease in area. 
Sampson Prairie—In the central mil- 
acre of the Sampson prairie, for plots of 
1/64-milacre size the average number of 
species was 3.79, the average number of 
individuals, 30.45. One of the plots of 
this size contained but one species, 4 ndro- 
pogon scoparius; the plot with the great- 
est number of species contained seven, 
Andropogon scoparius, Solidago nemoralis, 
Houstonia nigricans, Desmodium ciliare, 
Bouteloua curtipendula, Acave virginica, 
and Lecidea sp. 
Plots of 1/16-milacre size in the cen- 
tral milacre contained 3 to 10 species each 
and averaged 6.56 per plot; the number 
of plants averaged 121.81. Quadrats of 
1/4-milacre size in this milacre contained 
7 to 11 species each and averaged 9.5 per 
plot; the average number of plants was 
487.25. 
In the 9-milacre square, the species list 
compiled by 1/4-milacre units showed a 
range of 5 to 11 species and an average of 
7.33 per unit; plots of the 1-milacre size 
had 9 to 13 species each and averaged 
11.22. In the 9-milacre square, a total of 
18 species was found. Species not found 
in the central milacre but found in one 
or more of the 8 milacres surrounding it 
were Senecio plattensis, Carya sp. (seed- 
ling), Aster patens, Sisyrinchium albidum, 
and an unidentified moss. 
The 9-milacre plot formed a part of 
the staked 25-milacre square. Species lists 
were made for the 25-milacre quadrat by 
5-milacre strips. Three species, Juniperus 
virginiana, Kuhnia eupatorioides, and 
Helianthus divaricatus, not found in the 
9-milacre plot, were found in other parts 
of the 25-milacre quadrat, and brought 
the total to 21 species for the 25-milacre 
quadrat. 
The 50-milacre rectangle, fig. 10, 
downslope from the 25-milacre quadrat, 
was checked by 10-milacre strips. Twenty 
species were found in this 50-milacre area. 
Three species, Aster oblongifolius, Ely- 
mus canadensis, and Eupatorium altissi- 
mum, found here were not found in the 
25-milacre unit. However, the species of 
Carya, Opuntia, Sisyrinchium, and Hel- 
ianthus found within the 25-milacre square 
were absent from the larger area. In the 
75-milacre area, 24 species were present. 
Phegley Prairie—In the central mil- 
acre of the Phegley prairie, for plots of 
1/64-milacre size the average number of 
species was 3.94, the average number of 
plants, 20.95. In one of the plots of this 
size only one species, Andropogon sco- 
parius, with two individuals, was found; 
the plot with the greatest number of spe- 
cies contained eight, 4. scoparius, Soli- 
dago nemoralis, Houstonia nigricans, Ger- 
ardia sp. (possibly G. gattingeri), Lespe- 
deza stipulacea, Bouteloua curtipendula, 
Euphorbia corollata, and L. capitata. 
Plots of 1/16-milacre size in the cen- 
tral milacre contained + to 11 species each 
and averaged 7.13 per plot. The number 
of plants in plots of this size averaged 
83.81. Quadrats of 1/4-milacre size in 
this milacre contained 11 or 12 species 
