48 



relic of a former wider extension ot the association. In the Amboy 

 area most of the country is either forested or pastured, and the only 

 observed examples of bunch-grass were scattered f ragiiients along the 

 roadsides. The Dixon area formerly contained much bunch-grass, 

 but it is also now largely under cultivation. The Oquawka area is 

 more extensively forested, but some of the bunch-grass still remains 

 in the original condition. The Lcptolonia cognatiim consocies is es- 

 pecially well represented there. The bunch-grass association formerly 

 occupied thousands of acres in the Havana area, but most of it is 

 now under cultivation. 



In the three chief sand areas, at Hanover, Oquawka, and 

 Havana, the sand deposits lie, as has already been noted, on the east 

 side of a river, extending from the water's edge to the bluff. The 

 bunch-grass association is always separated from the river by a nar- 

 row or wide marginal forest, but may extend inland to the very base 

 of the bluffs, as at Hanover. It may then be di\ided into smaller 

 areas by transverse belts of forest, as at Havana. To these smaller 

 tracts local names are sometimes given, as Benton Prairie at 

 Oquawka. The tracts thus delimited are not unifonn, but each may 

 be occupied l\v two or more consocies. The different prairies of a 

 sand area are, howe\er, occupied in general by the same consocies 

 and have the same flora. But two noteworthy species seem to form 

 an exception to this rule, Brcivcria Pickcringii in Benton Prairie at 

 Oquawka, and LcsqiicrcUa argciitca \n the Devil's Neck region of the 

 Havana area. 



The bunch-grasses which gi\e the association its name produce 

 at the base or along the lower portion of the culm a number of leaves, 

 which are ag'gregated into loose or crowded bunches, depending upon 

 their size and number. Rising from their center are the flowering 

 culms, and beneath the living leaves are also the dried dead leaves 

 and culms of the previous season. The heig'ht of the bunches, ex- 

 clusive of the culms, is therefore, in most cases, approximately equal 

 to the length of the basal and lower leaves. In simple bunches all 

 the lea\-es and culms radiate from one center, and a bunch con- 

 sists of one plant, or rather of one stool. The diameter of the bunch 

 is then not more than twice the length of the basal leaves. Such 

 simple bunches are exhibited by Paniciiin pcrlongiim and Stipa 

 spartea. With some other species, as Panicuin psciidopubcscciis, the 

 culms are also spreading or horizontal, and the diameter of the bunch 

 is about equal to twice the length of the culms. In other cases the 

 individual plants are closely associated, so that the dense bunches 

 may reach any diameter, and are usually very irregular in shape. This 



