1608] VEGETATION REGIONS OF THE PRAIRIE PROVINCE — 389 
orpoophytic. Naturally, they occur throughout the three regions, 
The central portion of the prairie province possesses but a single 
type of meadow formation, the long-stemmed grass meadow, in 
which the facies are Elymus Canadensis, Stipa spartea, Agropyron 
pseudorepens, Panicum virgatum, Andropogon provincialis, and Spar- 
tina cynosuroides. This meadow formation exhibits a number of 
aspects in different stations. It is frequently reduced to a sin- 
gle facies. In sloughs and low meadows, this facies is Spartina 
yynosuroides; over certain upland meadows, it is Stipa spartea: 
The most common association of facies is that of Elymus Cana- 
densis, Panicum virgatum, Agropyron pseudorepens, and Andropogon 
provinciahs, which occur in meadows throughout, especially in 
the sand hills. The prairie and sand hill formations attain their 
fullest expression in their respective regions, but are not neces- 
sarily confined to them. Both prairie formations occur in the 
tty valleys of the sand hill region, and the bunch grass forma- 
tion of region III is found upon the sub-sand hills of the prairie 
fegion. Foothill formations, on the contrary, are restricted to 
their proper region. 
Prairie formations are of two types, the prairie grass, and 
the buffalo grass formation. The former covers the eastern 
Portion of the prairie region, Illinois, lowa, eastern Dakota, 
Nebraska and Kansas. The facies are species of Sporobolus, 
- Kecleria cristata, Eatonia obtusata, and Panicum Scribnerianum. 
- Frequently the facies of the meadow formations enumerated 
fbove assume sufficient abundance on the prairies to warrant 
Ranking them as facies of the prairie grass formation. Like 
Most formations of regions possessing a long growing period, 
- the prairie grass formation manifests two different temporal 
‘pects, a vernal and an estival-serotinal aspect. During the 
former, the ground-tone of the formation ‘5 due to the uniform 
2 Steen of its facies, which is slightly variegated by Dr aba ait 
@, Antennaria campestris, Anemone Caroliniana, Baptisia vet 
ree crassicarpus, etc. The << ewe ee 
a al aspect might well be separated, if the 0 ae <0 
_ Pass so gradually and completely into the other. 
