76 



Perennials : 



Petalostemiiui purpnremn Liatris scariosa 



Petalostemum candidwn Solidago iiciiwralis 



Euphorbia coroUata Solidago rigid a 



Callirhoc friangulata Hcliauthits scaberrimns 



Vernonia fasciculata Helianthus occidentalis 



Liatris cylindracea Artemisia caudata 



Interstitials (excluding grasses) : 



Polygonum tenue Crotoii glandulosns, var. 

 Mo'llugo vcrticillata septentrionalis 



Draba caroliniana Euphorbia Geyeri 



Arabis lyrata Oenothera rhombipetala 



Polanisia graveolens Monarda punctata 



Linuni sulcatum Erigeron ramosus 



Arabis lyrata is here sometimes veiy abundant and covers areas 

 five to fifteen feet (2-5 m.) across to the exclusion of almost all other 

 vegetation. These spots are always covered by gravel sorted out by 

 water action, affording an optimum habitat for the rock-loving plant. 



In the Oquawka area Paspalum setaceuui and blue-grass tend to 

 replace the bunch-grasses. The number of interstitials is increased, 

 and Monarda punctata, Erigeron ramosus, and Ambrosia psilo- 

 stachya become especially abundant. A few weedy perennials also 

 remain, such as Lactuca canadensis and Verbena stricta. 



Many of the roads across the sand prairies are little used and the 

 roadsides are occupied by a vegetation very similar to the original 

 bunch-grass. This is particularly true in the Hanover area, w'hich is 

 very sparsely settled. Even there Poa pratensis comes in and par- 

 tially converts the bunch-grass into sod. Thickets of Ribes gracile 

 and other beny-bearing shrubs come up along the fence-rows, and 

 their shade is a favorite habitat for Artemisia ludoziciana. Various 

 interstitials, especially Cassia ChamaecJirista, Digitaria Uliformis, 

 Mollugo verticillata, and Cenchrus carolinianus grow even in the 

 road-bed between the wheel-tracks. 



The same general conditions obtain in the Havana and Oquawka 

 areas, but wuth more travel because of the denser population the 

 original bunch-grass is destroyed or obscured by the numerous weeds 

 that follow civilization. These include tw^o groups, the first composed 

 of species normal to^ natural associations but flourishing also along* 

 the roadsides, and the second of true weeds, mostly natives of the 

 Old World and not found on natural sand associations in the vicinity. 



