BIG SPRING PRAIRIE. 6 
In treating of the plant societies of any region, it is 
not neccessary or even expedient to enumerate all the 
plants occurring in them. The rare or accidental ones 
are sometimes of interest only as they may be remnants 
of some past society or prophecies of some future one, 
generally difficult of interpretation. The common 
plants which give character to the landscape are the 
ones of most interest as they have proven their fitness 
of survival by their successful struggle with their rivals. 
‘The divisions under which the plants of these ridges 
can be divided are the Woodland Societies, The Road- 
side Societies, the Cultivated Field Societies, and the 
Pasture-land Societies, the last two constituting the 
troublesome weeds. ‘The Woodland societieis of the 
summits of ridges, steep slopes, and outcrops shall be 
considered separately from those of the median plane 
and drainage valleys, while in regard to the remaining 
societies, it is not necessary to thus subdivide them. 
The plants of the woodland areas are conveniently 
arranged under the horizontal strata of trees, shrubs, 
and herbs. ‘The forests on the summits of the ridges, 
the steepest slopes, and the outcrops of the Niagara 
limestone are xeromesophytic and of the White-oak, 
Black-oak, Hickory type of forest. 
Considerably over one-half of the trees are species 
of Quercus (Oak), less than one-fourth are Hicoria 
(Hickories), the remainder are a variable mixture of 
Cornus (Dogwood), Cercis (Redbud), Sassafras (Sassa- 
fras), Acer (Maple), Crataegus (Hawthorn), Juglans 
(Walnut) Celtis (Hackberry), and Ostrya (Ironwood). 
Of the latter the dogwood and redbud are perhaps 
the more abundant, the walnut the least abundant. 
The most characteristic tree is Quercus alba L. 
(White oak). The next most common ones of the oaks. 
are Quercus rubra L. (Red oak) and Quercus velutina 
Lam. (Black oak). Besides these, the following occur: 
Quercus minor (Marsh), Sarg. (Post or iron oak), 
