August. 1955 



EvERs: HiLi. Pr.airies of Illinois 



383 



Table 2. — Species and numbers of plant in- 

 dividuals in the central milacre of Sampson 

 hill prairie. 



Table 3. — Species and numbers of plant in- 

 dividuals in the central milacre of Phegley hill 

 prairie. ^ 



Species 



Andropogon scoparius. . . 



Houstonia nigricans 



Desmodium ciliare 



Solidago nemoralis 



Boulehua curlipendula . . . 



Andropogon gerardi 



Gerardia sp.f 



Petalostemum purpureum. 



Lespedeza capitala 



. igave virginica 



Euphorbia coroHala 



Opuntia rafinesquii 



Lecidea spp 



Number of Plant 

 Individuals 



1,404* 



141 



80 



64 



44* 



14* 



U 



9 



6 



2 



1 



1 



172* 



* Estimated. 



t Possibly G. gattingtri. 



10 different species were mapped and 

 counted ; in the central milacre of Pheg- 

 ley prairie, 436 plants of 14 species. Table 

 2 shows density for both grass and non- 

 grass species in the mapped Sampson mil- 

 acre ; table 3 gives similar information for 

 species in the mapped Phegley milacre. 



Total Densities. — In Sampson prairie, 

 the density in the mapped central milacre 

 was 1,949 plants; in Phegley, 1,341. 



In both prairies, grass-plant individuals 

 were more numerous than the nongrass 

 plants. In Sampson, 75 per cent of the 

 plant individuals were grasses and 25 per 

 cent were not grasses ; in Phegley, 67 per 

 cent were grasses and ii per cent were 

 not. It is of interest that the nongrass 

 species made up a higher percentage of 

 the individual plants in grazed prairie 

 than in ungrazed. 



Ground Space of Plants. — Ground 

 space uf plants is considered here as the 

 area occupied by the plants at ground sur- 



* Estimated. 



t Possibly G. sattingfri. 



t Small seedlings. 



face. The writer determined the ground 

 space for grasses, table 4, from the maps 

 of the central milacre of Phegley and 

 Sampson prairies by use of a planimeter. 



Phegley Prairie. — In the central mil- 

 acre of this pastured prairie, Andropogon 

 scoparius covered at ground level 1,107 

 square inches (71 square decimeters*), or 

 17.64 per cent of the milacre; Bouteloua 

 curtipendula occupied 138.4 square inches 

 (9 square decimeters), or 2.21 per cent 

 of the milacre, tables 4 and 6. The two 

 bunch grasses covered 1,245.4 square 

 inches (80 square decimeters), or 19.85 

 per cent of the quadrat at ground level. 



Most of the plants other than grasses, 

 437 individuals of 14 species, occurred in 

 the spaces between the grass bunches. The 



•Metric equivalents in this section on cToiiiid space ate 

 given to the nearest whole number. 



Table 4. — Ground space or areas square inches i occupied at (ground surface by the hunch 

 grasses in the central milacre of Sampson and of Phegley hill prairies. 



