.S82 



Illinois Natural History Survey Bulletin 



Vol. 25, Art. 5 



timated 1,157 grass-plant indi\iiluals or 

 tufts. This estimate was reached h\ di- 

 viding the numher of shoots in bunches 

 and patches (4,051) by the number of 

 shoots in a t\pical tuft (3 or 4, average 

 3.5). There were in addition 247 shoots 

 not aggregated into tufts or bunches. 

 These were considered individual plants, 

 as it was impossible to determine any un- 

 derground connections without digging 

 and removing these shoots from the mil- 

 acre. The estimated total number of in- 

 dividuals of A. scoparius was 1,404. 



In the Phegley prairie, the shoots of 

 Andropoyriii scopnrius were mostly short 

 and well separated, with very little lat- 

 eral extension of the foliage. The open 

 appearance of each bunch, the large pro- 

 portion of bare ground, and the consid- 

 erable ground area per shoot within the 

 bunches were attributed to grazing and 

 trampling b\ cows. Cows doubtless de- 

 stroyed many shoots either by pulling 

 them out or breaking them off and tiius 

 materialh reduced the number of shoots 

 per tuft. 



In the samples taken from ungrazed 

 hill prairie in two sites, Northeast Mere- 

 dosia and Reavis Spring, the number of 

 shoots per tuft averaged between 3 and 4. 

 In the mapped central milacre of the pas- 

 tured Phegley prairie, the number of 

 shoots per tuft was not so large; it was 

 conservative to place the number of shoots 

 per tuft at one-half that of ungrazcd prai- 

 rie, that is, 1.5 or 2.0, average 1.75. The 

 1,143 shoots in bunches thus formed an 



estimated b53 tufts or grass-plant individ- 

 uals. In addition, 196 isolated shoots, 

 representing that many isolated plant in- 

 di\'iduals, were counted. The estimated 

 total number of A. scoparius plants was 

 .S49. 



In the mapped Sampson milacre, 22 

 shoots of Andropogon gerardi were found; 

 19 of these occurred in one bunch. These 

 19 shoots formed 11 plant individuals 

 (estimated). With the 3 isolated plants 

 added, the estimated number of .7. ger- 

 (inli indi\iduals was 14. ./. gerardi did 

 not occur in the mapped milacre in the 

 Phegley prairie. 



In the central milacre of Sampson, 6 

 bunches of Bouteloua curtipendula with 

 -1-3 shoots were mapped. These b bunches 

 contained an estimated 12 plants. In ad- 

 dition, 32 isolated plants were counted. 

 The estimated number of indi\iduals of 

 H. curtipendula was 44. 



In the mapped Phegley milacre, 15 

 bunches of Bouteloua curtipendula with 

 lOS shoots were charted. These 15 

 bunches contained an estimated 31 plants. 

 In addition, 25 isolated plants were 

 counted. The estimated number of indi- 

 viduals of B. curtipendula was 56. 



The ungrazed Sampson prairie con- 

 tained an estimated 1,462 grass plants in 

 the central milacre; the grazed Phegley 

 prairie 905 in the central milacre. Table 1 

 summarizes the above data. 



Plants Other Than Grasses. — Of 

 plants other than grasses in the central 

 milacre of Sampson prairie, 487 plants of 



Table 1. — Shoot counts and estimated numbers ol bunch-grass plant individuals in the 

 mapped central milacre of Sampson and of Phegley hill prairies. 



