119 



the agency of animals. There are few animals to cany the acorns 

 out on the prairie. The majority of such acorns are eaten, and many 

 of the remainder decay. Some trees produce exceedingly heavy crops 

 of acorns, which lie in layers an inch or two (3-4 cm.) deep be- 

 neath the tree, but of a large number examined, not one was sound. 

 The life of a tree seedling is at best precarious, and in an unusual 

 environment, with full exposure to wind and sun, few of them may 

 be expected to survive. It is possible that some seasons are more 

 favorable than others, and that after intervals of several years a 

 succession of two or three favorable seasons may lead to a con- 

 siderable extension of the forest. This condition has been described 

 by Ramaley (ipo8: 30) and is probably of wide application. 



Establishment of the forest makes at first very little difference in 

 the environment. The trees are relatively far apart, and sufficient 

 light conies through the foliage to permit the growth of many 

 species of the original bunch-grass. The edge of the forest, there- 

 fore, shows, not a change in the flora but merely the addition of a 

 few^ other species. There are at present few places where the con- 

 tact between forest and prairie can be observed. Of these, the best 

 is in the Hanover area (PI. XIII, Fig". 2). The ground cover is the 

 usual climax growth of the mixed consocies of bunch-grass, consist- 

 ing particularly of Koeleria cristata and Andropogon scoparius. 

 With these are Boiiteloua hirsiita, Aster linariif olius , Aster seri- 

 cens, Call ir hoc triangiilata, and other common species. The sand is 

 in apparently the same condition as upon the prairie. The fallen oak 

 leaves have either blown away completely or have been collected in 

 piles around fallen branches and in thickets of Rhus canadensis, var. 

 illinocnsis. There is none of the additional herbaceous species typ- 

 ical of the older established forest. In the Winnebago area there are 

 a few small open spots within the forest, which represent the last 

 stages of a prairie. In the first of these there are Carex Muhlen- 

 hergii, Koeleria cristata, Liatris cylindracea, Lespedeza capitata, 

 Viola pedata, Polygala polygaina, and Artemisia caudata. Oak seed- 

 lings one or two years old w^ere also present. In a larger opening 

 (PI. XVII, Fig. i) the prairie character is more obvious. The domi- 

 nant species consist of a mixed growth of Paiiicuin Scrihnerianmn, 

 P. pcrlonguni, P. psendopiihescens, P. zirgatuui, and Carex Mnhlen- 

 bergii. Between their branches the ground is well matted with Cla- 

 donia. Some of the accessoiy species are Tephrosia virginiana, 

 Amorpha canescens, Lespedc^a capitata, Solidago nenioralis, Asclepias 

 amplexicanlis, Potentilla argiifa, Acerates znridiflora, var. linearis, 

 Viola pedata, and Ambrosia psilosfachya. There are no forest relics. 



