388 



Illinois Natural History Survey Bulletin 



Vol. 26, Art. 5 



each and aveiaj;ed 1 1 .5. The average 

 number of plants was 335.25 in this size 

 unit. 



In the 9-inilacre square, the species li-^t 

 compiled b\' 1 4-milacre units showed a 

 range of 6 to 12 species and an average 

 of 9.27 per luiit. The 1-milacre plot size 

 had a range of 11 to 16 species each and 

 an average of 13.44. Ten species not 

 found in the central milacre but found in 

 the surrounding eight were Andrnprniun 

 gerardi, Lccldea sp., Asti-r patfiis, Errii/rus- 

 iis spectabUis, Rhus copalliiia, Kuhnia eu- 

 patorifildes, Panicuni scribiicruinuni, Pon 

 praleiisis, RufUia huniilis, and a second 

 species of iiirtirdiii ( possibly G . asperii ) . 

 Twent\-si\ were found in the '^-milacre 

 quadrat. 



The 9-milacre plot formed a part of 

 the staked 50-mi!acre rectangle, fig. 10, 

 which was examined by 10-milacre strips. 

 Six species not found in the 9-milacre 

 square were found in other parts of the 



rectangle. These were Aster nblaniji- 

 I'llius, Opuntia rafinesquii, Tridens fitivus, 

 Mflil'i/iis alba, Rhus arornatica, and F.ri- 

 t/eron strigosus. The first four of these 

 were found onU in the 10-milacre strip 

 nearest the impru\ed pasture eastward 

 from the crest of the ridge. This strip, 

 because of its proximity to the pasture, 

 probabh' should not be considered tvpical 

 hill prairie. Two species not found in the 

 •'-milacre plot were found in other parts 

 of the four downslope 10-milacrc strips 

 and brought the total to 28 species. 



The 25-milacre quadrat downslope 

 from the 50-milacre rectangle yielded but 

 one species that did not occur in the 50- 

 milacre rectangle; this was Asclepias vh- 

 idif/ora. There were, however, seven spe- 

 cies in the four downslope 10-niilacrc 

 strips of the 50-milacre area that did not 

 occur in the 25-milacre unit. These were 

 Rlu/s (iipaUina. Kuhnia rupatorinides, 

 I'aiiiiuni SI ribinri/iini/ii . Pun prnlensis, 



Table 10. — Frequenc> (it occurrence of plant species in plots of five sizes, Sampson liil 

 prairie. 



Spf.cif-S 



Andropogon scoparius . . . . 



Hoiislonia nigricans 



Desmodium ciliare 



Solidcigo netnoridis 



Lespedeza capilata 



GerarJia gatlingerii ?).... 

 Boiileloua curlipendula.. . . 



Lecidea spp 



Andropogon gerardi 



Pelaloslemiim purpitreum. 



Senecio plallensis 



Euphorbia coroUata 



Agave virginica 



Opuntia rafinesquii 



Asler patens 



Gary a sp 



Sis\rinchiutn albiditni ... 

 Unidentified mos.s 



Size A 



(I 256 



Milacre, 



0156 



SlJlARE 



Meter) 



Num- 

 ber 

 of 

 Plots 



60 

 22 

 19 

 13 

 1 

 1 



12 

 4 



Per 

 Cent 



of 

 Plots 



93 8 



34,4 



29.7 



20.3 



1.6 



1.6 



18.5 



6.3 



1.6 



3.1 



U) species 

 64 plots 



SizK K 

 (1 64 



Mil. ACRE, 



0625 

 Square 

 Meter) 



Num- 

 ber 

 of 

 Plots 



64 

 49 

 42 

 32 

 5 

 II 

 17 



Per 



Cent 



of 



Plots 



100 



78,1 

 65,6 

 50 



7,8 

 17.2 

 26 6 

 12 5 



4,7 

 12 5 



16 

 3 1 

 1,6 



13 species 

 64 plots 



Size C 



(1/16 



MlLACRF, 



25 

 Sqiare 



Meter^ 



Num- 

 ber 

 of 

 Plot.s 



16 

 15 

 16 

 15 



5 



Per 

 Cent 



of 

 Plots 



too 



93,8 

 100 

 93.8 

 31 3 

 50 

 56 3 

 50 

 12,5 

 43,8 



6,3 



12 5 



6 3 



13 species 

 16 plots 



Size D 



(1/4 



Mn.ACRE, 



1,01 

 Square 



Meters) 



Num- 

 ber 

 of 



Plots 



36 



36 



33 



33 



24 



20 



18 



15 



14 



13 



7 



7 



2 



2 



I 



1 



1 



1 



Per 



Cent 



of 



Plots 



100.0 



100.0 



91.7 



91.7 



66,7 



55.6 



50.0 



41.7 



38 9 



36.1 



19.4 



19.4 



5,6 



5 6 



2.8 



2 8 



2.8 



2.8 



18 species 

 36 plots 



Size E 



(1 



Milacre, 



4 05 

 Square 

 Meiers) 



Num- 

 ber 

 of 



Plots 



Per 

 Cent 



of 

 Plots 



100 

 100 

 100 

 100 

 100 

 100 



88 9 



77.8 



66 7 



77 



44 



55 



22 



22 



11 



11 



11 



11 



18 species 

 9 plots 



