THE FLORA OF THE PRAIRIES. 583 
as properly eastern forms, while the entire absence of repre- 
sentatives of some large groups of trees and shrubs that are 
common at the East makes the difference greater than at first 
seems. One may traverse hundreds of square miles in the 
prairie districts without meeting a single birch, alder, a 
chestnut, beech, or aspen (Populus tremuloides Michx.), nor 
any species of pine, spruce, hemlock or other coniferous tree, 
all of which are so abundant in the forests of the Atlantic 
States as to constitute the prevailing species. Two species 
of cottonwood (Populus monilifera Ait., and P. angulata 
Ait.), so closely allied as to be confounded as one by the 
casual observer, but neither of them exclusively western, are 
probably the most characteristic trees, as they are certainly 
the most abundant and important. The sugar maple, the 
linden, elms, bitter-nut and other hickories (chiefly the 
former), butternuts, black walnuts, burr, white, black and 
other oaks, several species of ashes, the beautiful ash-leaved 
maple (JVegundo aceroides Mench.) and the locust (Ztobinia 
Pseudacacia Linn.), are the principal and almost the only 
important kinds of timber, the greater number of which are 
more or less common trees. Among the shrubs are several 
species of sumach (Rhus) and the hazel bush ( Corylus 
Americana Walt.), which here, as at the East, principally 
compose the thickets, whilst the Ceanothus, or Jersey tea, is 
a frequent inhabitant of the prairies. One searches in vain, 
however, for any whortle-berry bushes ( Vaccinium), of 
which so many species abound at the East, or for any repre- 
sentatives of the large family Hricacee, than which no fam- 
ily is more characteristic of the woodlands of the Eastern 
States. Viburnums are common, and the elder ( Sambucus 
Canadensis Linn.), the honeysuckle (Lonicera), the snow- 
berry (Symphoricarpus), and other caprifoliaceous shrubs 
are more or less frequent. The wild apple, the Washington 
thorn (Crategus cordata Ait.), and the wild plum are com- 
mon among the rosaceous shrubs, but blackberries and 
raspberries are rare. The wild plum grows in the river 
