GRASSLAND VEGETATION. 
Figure 31.—A sod cover formed largely by wheat grass and little bunch-grass. (Bunch-grass.) A 
profusion of coarse plants, such as gentians, composites, and umbellifers give a varied appearance to this 
grassland. Wheat fields are shown in the background. Pullman, Wash, 
Figure 32.—An open bunch-grass cover characterized by wheat grass. (Bunch grass.) Many plants 
from both the wheat-grass sod and the adjacent desert shrub occur in this vegetation. Conditions are more 
adverse in the bunch grass than in the sod. Near Pendleton, Oreg. 
_ 0 .nd South Dakota and Minnesota; and although the 
center of production of timothy and clover hay lies 
farther eastward, great quantities are also produced 
in the eastern portion of this prairie area. This region 
also produces great quantities of wild prairie hay. 
Alfalfa grown without irrigation is confined largely 
to the prairies of Kansas, Nebraska, and Oklahoma. 
The coastal prairies of Texas and Louisiana produce 
most of the rice grown in the United States. 
The tall grass vegetation may be subdivided into the 
following communities (fig. 3). In the following sec¬ 
tions the communities discussed in the larger type are 
true climax and are known as associations; those in 
smaller type are developmental for the most part and 
are associes. 
Bluestem sod grass. 
Bluestem bunch grass. 
Needle grass-slender wheat grass. 
Sedge prairie. 
Sand sage-aand grass. 
Shinnery. 
Broom sedge-water grass. 
Bluestem sod grass (fig. 27).—This is the most ex¬ 
tensive of any of the tail-grass divisions. It occurs 
over the greater portion of Illinois, Iowa, and eastern 
Kansas, and also in Missouri, Oklahoma, and Texas, 
and in western Minnesota and eastern North Dakota, 
South Dakota, and Nebraska. (Fig. 3.) The promi¬ 
nent grasses are bluestem ( Andropogon furcatus ), 
bunch grass ( Andropogon scoparius ), and Indian 
grass ( Sorghastrum nutans ), accompanied by other 
species. With these grasses there occur at times a 
great profusion of flowering plants. Of this type was 
the great prairie of the Mississippi Valley, in crossing 
which explorers traveled for many days through lux¬ 
uriant fields of grass. 
Over this area the soil is unusually rich, of good 
texture, and dark color, the result of its high humus 
content. The surface soil within the reach of the 
deep-rooted grasses is dried out each year, but the 
subsoil is permanently moist. The rainfall of 20 to 40 
inches comes largely in early spring and summer. In 
late summer and fall occur droughts, which were doubt¬ 
less largely responsible for the destructive prairie fires 
of the region. These droughts were probably as much 
the result of the luxuriant growth and consequent 
rapid expenditure of moisture as the lack of rainfall. 
Much of the best agricultural land of the United States 
was formerly covered by this type of vegetation (fig. 
4). The central portion of this area includes a large 
part of what is now generally known agriculturally as 
the Corn Belt. 
Bluestem bunch grass (fig. 28).—In passing west¬ 
ward the moisture supply becomes more deficient and 
plants assume the bunch habit of growth. In central 
Kansas and Oklahoma (fig. 3) this type is made 
up largely of bunch grass ( Andropogon scoparius '), 
together with grasses of the bluestem sod type and a 
slight admixture of the short grasses of the plains. In 
appearance this type is more varied than the bluestem 
sod and presents an open mixed cover. The type ex¬ 
tends along the boundary line of short and tall grasses 
from Nebraska to Texas, and occurs as isolated areas 
farther west on sand lands and stony open ground. 
In places bunch grass is practically pure, tending to 
dominate the area. Conditions for general agricul¬ 
ture are not as good in this type as in the bluestem 
sod, owing principally to the lesser moisture supply. 
The average annual precipitation is usually 20 to 30 
inches. The surface layer of moist soil is from 2 to 4 
feet in depth and there is no loss of moisture to the 
subsoil, which is permanently dry. The greatest winter- 
wheat areas in the United States lie within the area 
marked by this vegetation. 
Needle grass slender wheat grass (fig. 29).—Far¬ 
ther north, in Nebraska, the Dakotas, and Minnesota 
(fig. 3), needle grass ( Stipa spartea) and slender wheat 
grass ( Agropyron tenerum ) become relatively more 
important. This type forms a dense sod cover, but the 
plants are not as vigorous as the bluestem sod grasses 
farther south. The rainfall is also somewhat less (18 
to 30 inches), but at the same time the evaporation is 
also less. The soil is dark and is moist to a depth 
of 3 feet or more. The subsoil in much of the area is 
permanently dry. Here, as in the bluestem sod, herba¬ 
ceous plants play a prominent role. The greatest 
spring-wheat area in the United States has developed 
on land characterized by this type of vegetation. 
Sedge prairie (fig. 30).—Farther eastward, on the lower 
swampy, poorly drained lands, wet prairies or sedge prairies 
become prominent. Their vegetation is made up of sedges, 
rushes, and coarse grasses, such as bluejoint ( Calamogrostis 
canadensis), reed canary grass (Phalaris arundindcea) , slough 
grass ( Spartina miehauxiana) , sedges, rushes, and semiaquatic 
herbs. This grassland merges gradually into the true marsh 
grassland, and is probably treeless because of its swampy con¬ 
dition. It can not be made productive agriculturally without 
drainage. 
Sand sage-sand grass. —At the western edge of the bluestem 
bunch-grass land and extending out into the short grass, mostly 
in South Dakota, Nebraska, Colorado, Kansas, and Texas, large 
sandhill areas occur. These are covered either with bunch- 
grass or with sand sage-sand grass. The latter varies greatly 
in appearance. Among the prominent plants are sand sage 
(Artemisia filifolia), sand grass ( Calamovilfa longifolia) , and 
the grasses of the bluestem bunch-grass type. The moisture sup¬ 
ply is even less here than on the bluestem bunch-grass type, but 
the loose soil and open cover enable plants to continue grow¬ 
ing during long periods of drought. The open vegetation cover 
contains in addition to grass a large number of other plants. 
The soil is far too light for safe cultivation, owing to the 
danger of blowing when denuded. 
Shinnery. —Similar sand areas in Texas, Oklahoma, and New 
Mexico are covered with bunch grass assoicated with shin 
oak ( Quercus havardii). This oak seldom exceeds 3 feet in 
height and forms a dense low shrubby growth. This vegeta¬ 
tion, locally called shinnery, represents a transition to the 
southern desert shrtib, since on many of the sandhills it is 
interspersed with mesquite. 
Broom sedge-water grass. —Near the Gulf coast, from Texas 
to Florida, are extensive coastal prairies of broom sedge-water 
grass, dominated largely by water grass ( Paspalum sp.) , switch 
grass ( Panioum virgatum), broom sedges ( Andropogon glome- 
ratus, A. saocharoides) , and bluestem {A. furcatus), all of 
which can persist in a wet soil. This vegetation corresponds 
more nearly to the sedge prairie than to any other and at the 
lower margin merges almost imperceptibly with the marsh 
grasslands of the coast. In addition to the grasses many showy 
flowering plants occur. The rainfall is heavy, ranging from 
30 to 60 inches annually. These lands have proven to be valu¬ 
able for grazing and for cotton and rice culture. 
BUNCH GRASS (PACIFIC GRASSLAND). 
This grassland is composed of bunch grasses, occur¬ 
ring chiefly in the Western States—California, Oregon, 
Washington, Idaho, Montana, and Nevada. In Ore¬ 
gon, Washington, and California it occupies extensive 
areas, and in the Palouse region forms a relatively 
dense stand. Throughout the northern Great Basin 
this bunch grass type occurs at higher elevations below 
the conifer zone. It is characterized by a rich display 
of flowering plants. The condition under which bunch 
grass develops is that of a moisture supply insufficient 
for a dense stand of grasses. The rainfall varies from 
10 to 25 inches. Some of the moisture supply comes 
during the growing season, but at the beginning of the 
growing season moisture is usually present to a depth 
of several feet in the soil. If rainfall were confined 
to the growing period, short grasses would develop, 
and if a still greater proportion fell during the winter 
rest period it would give way to sagebrush. 
Although this type occurs in Arizona, New Mexico, 
Colorado, and Utah, it becomes of importance only in 
Washington, Oregon, and California. In Washington 
and Oregon it indicates the best wheat land of the 
Northwest. All of the area is valuable grazing land, 
and in California especially the bunch grasses have 
long since disappeared as a result of overgrazing, and 
only the weed grasses remain. Even in the Northwest 
the bunch grasses are being rapidly killed out by over- 
grazing. 
The bunch-grass vegetation may be divided into the 
following communities: 
Wheat-grass sod. 
Wheat-grass bunch. 
Stipa-Poa-bunch grass. 
Wheat grass sod (fig. 31).—In the eastern portion of 
Oregon and Washington (Palouse region) (fig. 3), 
where the moisture conditions are more favorable, this 
grass produces a sod which contains, in addition to 
wheat grass (. Agropyron spioatum) , the little bunch 
grass ( Festuca idahoensis) , poa {Poa sandbergii) , and 
balsam root ( Balsamorrhiza sagittata ). During the 
early spring and summer this area presents a luxuriant 
and varied appearance, due largely to the prominence 
of plants with large, showy flowers and leaves. The 
rainfall is from 15 to 25 inches. Within the area 
marked by this type lie the best wheat lands of the 
Northwest. 
Wheat-grass bunch (fig. 32).—In the western por¬ 
tion of the northwest prairie, where the moisture sup¬ 
ply is deficient, or the soil less able to hold available 
water, due to its shallow or rocky character, this plant 
cover presents an open bunchlike appearance. It is 
composed of wheat grass ( Agropyron spicatum) either 
alone or mixed with poa ( Poa sandbergii ) and con¬ 
spicuous herbaceous plants. This type marks the 
transition from the wheat-grass sod to the sage¬ 
brush desert. It occurs in areas receiving from 15 
to 20 inches of precipitation, and is widely distrib¬ 
uted, especially in the northern portion of the Great 
Basin (fig. 3). It is interesting to compare the be¬ 
havior of such grasses as wheat grass ( Agropyron 
spicatum ) and bunch grass (- Agropyron scoparius ’). 
Both are sod formers when sufficiently supplied with 
water, and both assume the bunch habit under more 
arid conditions. In both cases the cause is a deficient 
moisture supply which causes grasses, as well as shrubs 
and trees, to develop only in open stands. Overgraz¬ 
ing is rapidly reducing this grassland to the weed-grass 
type discussed below. 
Btipa-poa bunch grass (figs. 33 and 34).—The great 
central valleys of California, the San Joaquin and Sac¬ 
ramento, also the Salinas and other valleys along the 
west coast, were first settled by the Spaniards and de¬ 
voted to stock raising. On the arrival of the settlers 
from the Eastern States the natural vegetation of this 
area did not differ essentially from its present condition. 
Along the streams were scattered groves of live oak 
('Quercus agrifolia and Q . wislizenii) and valley oak 
(' Quercus lobata), and the areas between were occu- 
