202 Nebraska State Horticultural Society.' 



Black Jack Oak (Quercus marilandica Muench.) of the Missouri 

 forests, has moved into the southeastern counties of Xobraska, Richard- 

 son to Pawnee and Nemaha. 



Laurel Oak (Quercus imbricaria Michx.) is found in the Missouri 

 forests, from which it has moved northwestward nearly or quite to 

 the southeastern corner of Nebraska. Although this species has re- 

 peatedly been reported from this part of the state, I have seen no 

 specimens which were collected within our borders. I have specimens 

 collected in Missouri but a short distance from the southeastern ex- 

 tremity of Nebraska. 



DISCUSSION. 



From the foregoing statistics it appears that of the seventeen 

 trees whose fruits or seeds are winged, thirteen came into Nebraska 

 from the southeast and four from the west. Of the eleven species with 

 hairy seeds six came from the southeast and five from the west. Of 

 the twenty species with fleshy fruits sixteen came from the southeast, 

 and four from the west. The single species whose seeds are in rolling 

 balls came from the southeast, and all of the species with edible nuts 

 (eighteen) came from the southeast. The significance of these facts 

 is not at once very obvious. They do not directly indicate the relative 

 value of the several devices for dissemination, nor do they plainly de- 

 cide the question of the efficiency of winds, waters, birds, and quadru- 

 peds as carrying agents. Thus the fact that thirteen trees with winged 

 fruits or seeds came from the southeast, and only four from the west, 

 does not indicate the greater efficiency of the southeast winds over 

 those from the west. The fact that there is a much more compact 

 forest area, containing a greater number of species of trees of this kind 

 a short distance southeast of the state, is of far greater importance. 

 The nearness of a vigorous vegetation representing many species makes 

 that vegetation more efficient in invading a territory. The Missouri 

 forests dominate the forests of Nebraska, because they are near by, 

 and contain many species. This is shown more emphatically in the 

 case of the species with edible nuts, all of which have come from the 

 Missouri forests, where they are abundant. In Wyoming and northern 

 Colorado there are no species of this kind in the sparse forests within 

 a hundred miles of the western border of Nebraska. There are no 

 oaks, hickories, walnuts, or buckeyes in this portion of the Rocky 

 mountain foothills to move eastward. On the other hand, there are 

 species of trees having hairy seeds not only in the Missouri forosts, 



