



The Atlantic Slope Naturalist. 



Vol. 1. 



NARBERTH, PA., JULY AND AUGUST, 1903. 



No. 3 



Distribution of Forest Trees on the 

 Nebraska Plains. 



By Charles E. Bessey, Ph.D., LL.D., 



Professor of Botany in the University of Nebraska, 

 Lincoln, Neb. 



I have been studying the forest 

 problems of Nebraska for many years 

 and have been able to make out a few- 

 interesting things in regard to them. 



In the first place, Nebraska has a very 

 small forest area, but it is exceedingly 

 interesting for all that. The forest trees 

 of the State number between sixty-five I 

 and seventy, depending somewhat upon 

 the interpretation of "tree" which is 

 given by the observer. These trees have 

 all come into the State, as I think, within 

 comparatively recent times, and we have 

 excellent opportunity for observing the j 

 mode of their entrance. The species 

 have entered the State very largely from 

 the southeast. If we pass down the 

 Missouri River and its tributaries south- ! 

 eastwardly we find an increasing number 

 of species, and many species which are 

 found within a short distance from the 

 southeastern corner of Nebraska do not 

 enter it. 



A map showing the distribution of the 

 species of trees in Nebraska shows fifty 

 or more in the extreme southeastern 

 corner of the State, and going northward 

 and westward from this point the number 

 rapidly decreases until finally not more 

 than eight or ten continue across the 

 State. It should be remembered that 

 the Missouri River is bordered by an 

 extension of the eastern forest area, and 

 that Nebraska lies with its eastern edge 

 in this eastern forest extension, while its 

 western edge is next to the Rocky 

 Mountains. 



As we pass westward across the State 

 the elevation above the sea rises from 

 less than a thousand feet to about five 

 thousand feet. The western portion of 

 the state is really an extension of the 

 eastern foot-hills of the Rocky Moun- 

 tains. Now it is found that ten species 

 of the Rocky Mountain trees have in- 

 vaded Nebraska from the west and have 

 pushed down eastward on the ridges 

 which maintain longest the foot-hills 

 conditions. Thus, the Bull Pine, so 

 common in the Rocky Mountains, the 

 western Red Cedar, four species of 

 Cottonwood, the Buffalo Berry, one 

 maple, and two birches have invaded 

 Nebraska from the west. 



This short note will serve to give the 

 botanist some idea of the interesting 

 distribution of forest trees which Ne- 

 braska shows. 



Crossing and Infertility. 

 By Morris Gibbs, H. D., Kalamazoo, Mich. 



In the study of evolution of the species 

 it is interesting to note the changes that 

 are the result from crossing among birds 

 and animals. Among the lower forms of 

 animal life we find a condition of con- 

 stancy, equal, and sometimes superior to 

 the standard observable in the higher 

 forms. For instance, there is a condition 

 of dimorphism and polymorphism in 

 many of the insects ; a condition of sea- 

 sonal change in form or size in different 

 broods of the same species. But this 

 change is almost invariable from year to 

 year, as carefully observed, and no radical 

 variation is seen, the types of each brood 

 maintaining the standard as previously 

 noted. Again we have the peculiar con- 

 dition of what is known as parthonogen- 



