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Interstitials : 



Pestitca octoflora Croton glandiilosiis, var. sep- 

 Cyperus Uliciilmis tentrionalis 



Rnmex Acctosclla Oenothera rhonihipctala 



Polygonum tenue Monarda punctata 



Silene antirrhina Hedeoma hispida 



Arabis lyrata Linaria canadensis 



Lepidiuni virginicum Specularia perfoliata 



Cassia Chaniacchrista Brigeron annuus 



Linuni snlcatmn Brigeron ramosus 



Polygala incarnata Ambrosia psilostachya 



Of the grasses in the above Hst, Bouteloiia hirsnta is most abun- 

 dant in the Oquawka area, and may usually be found in any of the 

 narrow strips of sand between the bunches of Leptoloina, although 

 its small size makes it very inconspicuous. Near Hanover, Bouteloua 

 does not occur in this consocies, and Panicum Scribnerianum and 

 Paniciiiii perlonguin are important secondaiy species. The others 

 are usually infrequent but are sometimes very conspicuous if the 

 bunches are of larg-e size and overtop the Leptoloma. Those of An- 

 dropogon scoparius and Carex Muhlenbergii contrast especially with 

 Leptoloma both in size and color. 



In the Hanover area the most abundant perennials are Buphorbia 

 corollata and Helianthus scaberrimus ; in the Oquawka area, Ruellia 

 ciliosa and Baptisia bracteata. Many of the perennials are conspicu- 

 ously taller than the Leptoloma and stand out in prominent relief 

 above it. This is especially true of the bushy shrubs Ceanothus 

 americanus, Rhus canadensis, var. illinoensis, and Amorpha can- 

 escens. 



Antennaria is the most abundant mat, and is frequent throughout 

 the consocies. The mats are small because of the limited space avail- 

 able. Senecio Balsamitae forms dense patches two to three feet 

 (5-10 dm.) across and shows some tendency to resist the encroach- 

 ment of the bunch-grasses. 



Of the interstitial plants, Ambrosia psilostachya is omnipresent, 

 and is represented by an immense number of individuals. Runiex 

 Acetosella and Monarda punctata are also very abundant. The lat- 

 ter is one of the most conspicuous features of the serotinal aspect. 

 Oenothera rhombipeiala is not so abundant as Monarda, but is equally 

 conspicuous at its blooming season during the aestival aspect, be- 

 cause of its taller stems and vivid yellow flowers. The other in- 

 terstitial plants vary greatly from place to place, and almost any 



