GRASSLAND AND DESERT SHRUB VEGETATION. 
Figure 43.—Sawgrass marsh. (Marsh grass.) Hummocks in background. The great coast marshes 
are inundated at high tide by salt water, but have not become excessively saline. In many places, such as 
the Everglades, the water-supply is practically entirely fresh. There is great variation in the botanical com¬ 
position of the marshes, but the type shown in the picture is very extensive. Near Detroit, Fla. 
Figure 44.—Pure tule marsh. (Marsh grass.) This is the most prominent type in the western 
marshes. Often the water is relatively rich in soluble salt. This type is extensive in the Klamath Lake 
region of Oregon and characterizes large areas in both the San Joaquin and Sacramento Valleys. Klamath 
Lake, Oreg. 
very fertile farm areas, especially for the production of 
asparagus, onions, potatoes, and barley hay. In south¬ 
ern Louisiana, where land of this type is being drained 
and used for rice production, and in the Everglades, 
where an attempt is being made to develop muck land 
into hay and truck farms, the land has been greatly 
modified by drainage. 
ALPINE MEADOW (ALPINE GRASSLAND). 
The alpine type occupies much of the mountain land 
above the timber line (figs. 2 and 3), and is dominated 
by rock sedge {Carex rupestris ), alpine nigger wool 
{Carex elynoides ), alpine fescue (Festuca brachyph- 
ylla), and a great variety of alpine plants, most of 
which are attractive to botanists as well as to tourists. 
During early summer it often presents a mass of bright 
colors, due to the blooming gentians, primroses, saxi¬ 
frages, foreget-me-nots, painted-cups, buck¬ 
wheats, lupines, polygonums, erigerons, etc. 
(fig. 45). The flora is especially rich, and 
many species essentially Arctic occur. The 
total area in the United States is relatively 
small, although Colorado, the northern 
Rockies, and the Cascade-Sierras have rather 
large areas of this type. The area shown on 
the map incliides also the great rock-fields, 
which have only cliff plants and lichens, and 
the snow fields and glaciers, which are devoid 
of vegetation. 
DESERT SHRUB VEGETATION. 
The desert shrub, with all its variations of 
plant cover, may be reduced to three general 
types: 
Sage brush, or northern desert shrub. 
Creosote bush, or southern desert shrub. 
Greasewood, or salt desert shrub. 
The Great Basin region in Utah, Nevada, 
and Oregon and similar areas in northern 
New Mexico, Arizona, and California may be 
characterized as sagebrush desert (fig. 2). 
The characteristic plants are small deciduous 
shrubs, deep-rooted for the most part, capable 
of enduring long periods of rest due either to 
drought or cold, and with growth limited by 
available water and favorable temperature. 
Cacti are characteristically absent from this 
desert. The rainfall is rather evenly distributed 
througout the year and for the most part is low, vary¬ 
ing from 5 to 15 inches. The character of the vegeta¬ 
tion indicates usually the amount of water available 
for growth. Throughout the area drought may occur 
at almost any time, and the plants, although well 
adapted for extreme drought, are often killed by pro¬ 
longed dry periods. The appearance of the vegetation 
is monotonous, and the traveler is impressed by the 
great expanse of pure stands of a single species. 
The southern portion of the Great Desert may be 
characterized as the creosote-bush desert (fig. 2). The 
evergreen creosote bush is as prominent in the southern 
desert as the sagebrush in the northern desert. Mes¬ 
quite ranges throughout this southern area, although it 
is relatively more important in the eastern part. 
Yucca, cacti, and spiny desert shrubs are often promi¬ 
nent. The water supply varies greatly, and prolonged 
droughts may occur at any time. In the drier portion 
the average rainfall may be as low as 2 inches per year, 
with droughts lasting from 2 to 6 months, or in 
extreme cases for a year or more. In other sections 
the rainfall may be as much as 20 inches and have a 
fairly even distribution. In this region there are two 
rainy periods, one in winter and one in summer (with a 
tendency toward a spring and fall maximum in the 
southeastern portion), and growth is limited by mois¬ 
ture supply and little or not at all by low temperatures. 
The appearance of this desert is markedly different 
from that of the northern desert. On the whole the 
plants are larger, more luxuriant, and more widely 
spaced. Many of them are succulent or evergreen and 
hold their leaves during the long periods of drought. 
In the southern portion, especially in the regions of 
comparatively high rainfall, such as southeastern Ari¬ 
zona, New Mexico, and Texas, this type is mixed with 
the desert grassland area. On the west this desert 
merges gradually into chaparral. 
At lower elevations than the sagebrush and the 
creosote-bush deserts is the greasewood desert, border¬ 
ing the drainage channels and occupying undrained 
basins, especially those underlain by artesian water 
(fig. 2). This type differs from other desert types in 
being limited largely to wet or subirrigated land con¬ 
taining a high percentage of soluble salts. Its most 
characteristic plant is the greasewood, which presents 
to the eye during periods of active growth a deep- 
green luxuriant appearance. Most of this desert is 
characterized by green, fleshy-leaved plants, and to 
one unaccustomed to alkali deserts it seems much less 
desert like than the drier areas of sagebrush or creosote 
bush of higher elevations. Over most of its area this 
desert is limited to tracts only a few miles across, and 
only the larger districts can be indicated on the map. 
SAGEBRUSH (NORTHERN DESERT SHRUB). 
This group is characterized by a scattered open 
stand of deciduous shrubs, almost all of which have 
small leaves of a light or silvery color. (Figs. 46 to 
50.) The plants are woody and seldom exceed 50 years 
in age. The plant cover usually consists of a single 
perennial species, the individual plants of which are 
unusually uniform in size and general habit. These 
great expanses of silver or ash colored vegetation 
present a monotonous appearance. 
Of the three types of desert vegetation, sagebrush is 
the most extensive. Although at high altitudes sage¬ 
brush extends to the Mexican boundary, it occurs only 
as small isolated patches south of latitude 34°. From 
latitude 37° north to the Canadian line most of the 
lower valley or basin land between the Cascade-Sierra 
on the west and Continental Divide on the east is occu¬ 
pied by this type of vegetation. It also occurs 
in the upper part of the Rio Grande basin and 
in the Bighorn, Laramie, and Casper basins in 
Wyoming. In a somewhat modified form it 
pushes far into the grassland areas of the Great 
Plains, especially in Montana and Wyoming, 
where it occurs as a dwarfed sagebrush alter¬ 
nating with grassland, especially in the Yel¬ 
lowstone, Missouri, North Platte, and Bighorn 
drainage basins. It also occurs in Colorado 
along the eastern base of the mountains, espe¬ 
cially in the valley of the Arkansas. 
This northern desert shrub type pushes into 
the short grass type of vegetation chiefly as 
sagebrush; into the bunch grass (wheat-grass 
bunch) as sagebrush, bitterbrush, or scabland 
sage; into the pinon-juniper as sagebrush or 
small sage; and into the southern desert as 
shadscale. As a rule the line of demarcation 
is not sharp between the sagebrush and pinon- 
juniper, but sharp alternations occur, the sage¬ 
brush usually occupying the better type of 
soil and the pinon-juniper the more rocky 
soils. The desert shrub extends into the drier 
valleys east of the Rocky Mountains in the 
north, while the short grass pushes into the 
desert areas west of the mountains, especially 
in the south. 
This great area of sagebrush desert is char¬ 
acterized by rainfall which is comparatively 
uniform throughout the year, being least dur¬ 
ing the months from July to September. Over 
much of the area the rainfall is less than 
10 inches and in very little, if any, of the area does it 
exceed 15 inches. The rainfall comes largely during 
the long winter rest period and finds its way deep into 
the soil. Many of the characteristic plants are deep- 
rooted. The evaporation rate is relatively high and 
the total amount of annual growth small. The frost- 
free period varies from 90 to 150 days, but the growing 
period is usually much shorter on account of drought. 
This great unit of vegetation is by no means uniform 
and may be subdivided into several types dominated 
by a practically pure stand of a single perennial species. 
Agriculture in the northern desert is limited to local 
areas. The best of the sagebrush land has been utilized 
for grain production under dry-farm methods, while 
a considerable area in many of the larger valleys of 
Idaho, Utah, and Nevada has been put under irrigation. 
Both winter and spring wheat, oats, barley, and rye are 
grown. Alfalfa is one of the most important crops of 
Figure 45.—Alpine grassland made up of grasses and sedges, with many low-growing, showy 
flowering plants. (Alpine meadow.) Timber line shown below. The flowers in the foreground 
are Polygonum bistortoides and painted brush (Castilleja occidentalis). Above Lawn Lake, 
Colo. Photographed by Wiswall Brothers. 
