ECOLOGICAL NOTES ON THE MUSCA TINE FLORA. 185 



The panicle of Panicum virgatum is much reduced, and in many- 

 cases the leaves are hairy. The annual grasses are abundantly repre- 

 sented by Triodia purpurea^ and such common weeds as Ccnchrus 

 tribuloides and Paniciiui sangiiinalc. 



Bluff Vegetation. — The physiography of the bluff region is sim- 

 ilar to that occurring northward. In the immediate vicinity of Mus- 

 catine is a fine loess. The hills are decidedly irregular, but in most 

 cases the elevation is not great. The hills gradually slope towards 

 the river. The small streams run in an easterly direction, passing 

 through the narrow eroded valleys. The larger hills, like Wyoming, 

 show out-crops of carboniferous sandstones, which again appear along 

 Pine creek, where bold sandstone ledges face the creek. Sufficient 

 erosion has taken place to form small caiions not unlike those of the 

 dells of the Wisconsin river. The hills are covered with a clay soil, 

 heavily timbered towards the valleys. Along the Mississippi the 

 slopes are more gradual, and in places form large, open grassy 

 meadows. 



Zonal Vegetation. — Mississippi alluvial — This does not differ 

 materially from that described for the bayou of Muscatine Island. 

 Except in a few cases Carya oliviEforinis was noted, and fine, large 

 specimens of Fraximis Americana^ Gyuinocladus Canadensis^ Agrostis 

 pcrennans, Leersia Virginica and Elynius Virginiciis. Along the edges 

 of the timber were large quantities of Coreopsis aristosa, Eupatoriuni 

 and Polygo)inni diinietorum^ var. scandcns. 



Triodia cuprea sone. — Above the alluvial drift to the edge of the 

 timbered area at Wyoming Hill, Triodia cuprea grows in large masses. 

 The dry banks are covered with this beautiful grass. It has spread 

 for some miles north and south along the railroad. Liatris cylindracca, 

 Andropogon furcatus and Kaleria cristata are found, but less com- 

 monly. The wooded area is marked by the abundance of Lespedeza 

 procunibens, Asprella hystrix, Quercus rubra and Carya alba. 



Carboniferous Sandstone Vegetation. — The region here consid- 

 ered is locally known as " Wild Cat Den " and occurs along Pine creek 

 north of Sweetland. The region is an extremely interesting one. The 

 flora represents an island where some northern and southern species 

 have been preserved. It is isolated from the prairie species to the 

 west and the common woodland forms along the river. The region 

 owes its peculiar vegetation to climate, as well as physiographic con- 

 ditions prevailing. 



The sandstone is retentive of moisture and releases its moisture 

 more slowly than limestone rock or the prairie region. Since it is 

 densely covered with timber, snow remains longer during the spring 

 and the plants are better protected than on the treeless prairies. 



