57 



Slipa spartea is the dominant grass, with Foa prafciisis second 

 in abundance. The bunches of Stipa are here more or less confluent, 

 and the intervening" spaces are sO' occupied by bkie-grass that the sur- 

 face of the sand is completely covered. This leaves no opportunity 

 for the growth of the usual interstitial plants and also tends to limit 

 the number of perennials. But four species occur and they are rep- 

 resented by few individuals. They are Paniciini pseudopubescens, 

 Callirhoe triangulata, Corc'opsis paliiiafa, and Aster linariifolius. All 

 of these are common in other consocies of the same association. 



At either side the consocies changes rather abruptly into an- 

 other characterized by Koclcria cristata, which has larger open spaces 

 between the bunches and permits the growth of more secondary 

 species. 



Tlie Koeleria cristata Consocies 



In the Hanover area this is by far the most important consocies 

 of the bunch-grass association which is characterized by a single 

 species, and in area is second only to the mixed consocies. If its 

 present extent may be taken as an index, it must originally have 

 covered hundreds of acres of the sand prairie, although in scattered 

 patches of rather small size. It is found alike on the sides and tops 

 of the hills, but seldom in the depressions between them. Elsewhere 

 the consocies was not observed. 



The dominant species is Koeleria cristata. The bunches of this 

 grass are mostly separate and compact, occupying from one half to 

 two thirds of the surface. The dead basal leaves cover the sand be- 

 tween the bunches, and make an efficient protection against blowing. 

 Pamciiin psciidopuhcscejis, which flourishes where the sand is largely 

 bare, is also frequently well developed. 



The number of secondary plants is large because of the unusual 

 amount of ground space available, and comparatively manv species 

 are represented. The number of individuals of the interstitial species 

 is especially large. The mats of Sclaginella rupestris reach here 

 their maximum size; regular circles up to three feet (i m.) in di- 

 ameter are common, and they may become confluent to fonn solid 

 masses eight to ten feet (2-3 m.) wide. Koeleria cristata lives in- 

 discriminately upon these mats or between them, and so do most of 

 the perennials. Panicuin pseudopubescens and the annuals are sel- 

 dom found except on the bare sand between them. The centers of 

 the Selaginella mats are usually covered with a black crust, upon 

 W'hich a species of Cladonia is frequently growing. Antennaria sp. 

 may grow on the mats also, or in the al)sence of Selaginella fonn 



