335 



which is not subsequently occupied by Potentilla fruticosa. In other 

 words, ground that is covered with a good stand of Potentilla fruti- 

 cosa is more easily invaded by prairie than by oak. 



LIST OF THE SPECIES OE THE POTENTIEEA FRUTICOSA ASSOCIATION 



Dominant Species 

 Potentilla fruticosa 



Secondary Species 



Senecio halsainitae 

 Hahenaria dilatata 

 Habenaria hyperhorca 

 Sisyrinchium sp. 



Relic Species 

 Buphorbia corollata 

 Rudheckia liirta 

 Suiilacina stcllata 

 Anemone cylindrica 

 Lithospernmm giiielini 

 Solidago nem oralis 

 Pinus strobus (by cutting) 

 Arabis lyrata 

 Potentilla anscrina 

 Blynius canadensis 



Invading Species 

 Pycnanthcni uni virginianuni 

 Krigia auiplexicauUs 

 Liatris spicafa 

 Pinus strobus (few) 

 Brigeron ramosus 

 Petalostcninni candidnm 

 Lobelia s pic at a 



Hypericum kalmianum 



Solidago graminifolia 

 Cladonia spp. 

 Mosses 



Artemisia caudal a 

 Jnniperns hori^ontalis 

 Arctostaphylos nva-ursi 

 Arenaria stricta 

 Ceanothus americanus 

 Calam ovilfa longifolia 

 Trad esc antia reflexa 

 Pteris aqnilina 

 Osmunda regalis 



Prunella vulgaris 

 Spiraea salicifolia 

 P rag aria virginiana 

 Poa compressa 

 Sali.v spp. 

 Bromus kolmii 



THE EIATRIS SPICATA PRAIRIE ASSOCIATION 



Spread over the low ridges of the southern part of the Beach 

 area occurs the best development of the southwestern or prairie 

 element of the flora of this region. In the forested parts of the 

 region the prairie associations occupy belts or zones between the 

 swale assocations and those of the forest. The area between the 

 Dead Lake and the Chicago and North Western railway, which was 



