Bouteloua curtipendula, commonly known as sideoats grama, is a perennial, short prairie grass that is native throughout the temperate and tropical Western Hemisphere, from Canada south to Argentina.
Sideoats grama is a warm-season grass. The culms (flowering stems) are 30–100 cm (12–39 in) tall, and have alternate leaves that are concentrated at the bottom of the culm. The leaves are light green to blue-green in color, and up to 6 mm (1⁄4 in) across.
The flowers bloom in summer and autumn. They consist of compact spikes that hang alternately in a raceme along the top 15 to 25 cm (6 to 10 in) of the culm. The spikes often fall to one side of the stem, which gives the plant its name. There are 10–50 spikes per culm, and in each spike there are three to six spikelets, or rarely as many as 10. Each spikelet is 4.5 to 10 mm (3⁄16 to 13⁄32 in) long and consists of two glumes and two florets. One of the florets is fertile, and has colorful orange to brownish red anthers and feathery white stigmas during the blooming period, which contrasts with the pale green, pale red, greenish-red, or purple color of the spikes themselves.
After blooming, the spikes become straw-colored. The fertile florets produce seeds, and when they are ripe, the spikes fall to the ground.
Sideoats grama grows well on mountainous plateaus, rocky slopes, and sandy plains. It is drought- and cold-tolerant and is hardy in USDA hardiness zones 4–9 (average annual minimums of −30 to 25 °F, −34 to −4 °C).
Sideoats grama is considered a good foraging grass for livestock. It is planted for erosion control.
Sideoats grama is a native, warm-season perennial grass that grows 3 to 39 in
(8-100 cm) tall [78,196]. Bouteloua curtipendula var.
curtipendula culms occur singly or in small clusters from creeping rhizomes,
while B. curtipendula var. caespitosa culms are in large clumps
arising from a common root crown . Sideoats grama leaves are 0.11 to 0.15 inch (3-4
mm) wide and flat at maturity [78,93]. Inflorescences are elongate and may bear over 20 and up to 80 deciduous spikes
[49,78,105], each of which bears 3 to 8 spikelets hanging to one side [78,93,128]. The fruit is an awnless caryopsis .
Sideoats grama typically has many coarse, fibrous roots , which may grow 2
to 4 feet (0.6-1.2 m) in length and spread laterally 1 to 1.5 feet (0.3-0.5 m)
in the top 2 to 4 inches (5-10 cm) of soil . In a Nebraska study sideoats
grama plants had a range of 170 to 423 roots per
plant . Roots of sideoats grama are well adapted to growth in dry
conditions . They extend rapidly into wet subsurface levels, reducing plant
dependency on more variable moisture conditions at the surface
soil . More information on drought resistance of sideoats grama is included
in Management Considerations.
Sideoats grama generally occurs in dry woods in the eastern United States and in
dry prairies and sandhills in the western states .
It is a major species in grasslands of the Great Plains, including tallgrass
prairie [113,174], mixed-grass prairie and shortgrass steppe [110,118], and in desert grasslands of the
Southwest . Sideoats grama
is also found in ponderosa pine (Pinus ponderosa) forests, eastern hardwood
savannas , southwestern oak (Quercus
spp.) and pinyon-juniper (Pinus-Juniperus spp.) woodlands and
savannas [112,165], and desert and semidesert
shrublands . Sideoats grama is commonly associated with bluebunch wheatgrass (Pseudoroegneria spicata),
western wheatgrass (Pascopyrum smithii), little bluestem (Schizachyrium
scoparium), big bluestem (Andropogon gerardii var. gerardii),
Idaho fescue (Festuca idahoensis), prairie Junegrass (Koeleria
macrantha), blue grama (Bouteloua gracilis), black greasewood (Sarcobatus
vermiculatus), true mountain-mahogany (Cercocarpus montanus),
southwestern oaks, Colorado pinyon pine (Pinus edulis),
and several juniper species including redberry juniper (Juniperus pinchotii),
eastern redcedar (J. virginiana), oneseed juniper (J.
monosperma), Ashe juniper (J. ashei), alligator juniper (J.
deppeana), and Utah juniper (J.
The following list of publications includes selected classifications listing
sideoats grama as an indicator or dominant species in vegetation classifications.
Sideoats grama reproduces apomictically
or sexually . Apomixis occurs in the southern range of sideoats grama, most commonly within
the range of Bouteloua curtipendula var. caespitosa. Sideoats
grama has perfect flowers  that cross pollinate .
In plants reproducing sexually, cross pollination is effected by wind .
Sideoats grama produces a "fair amount of seed of
rather low viability"  but seeds readily when adequate moisture is
available . There are several cultivars of sideoats
grama (see Management Considerations) with
varying seed productivity.
Awnless fruits suggest that sideoats grama seed is dispersed mainly by wind .
Little direct information is available about seed
banking of sideoats grama, but several studies indicate that seed banking of
sideoats grama is minor, and varies with local conditions. A study
of seed banks in postsettlement vegetation communities in the Loess Hills of
Iowa found sideoats grama had low seed density (<25 seeds/m2) in the
seed bank of a shrubland site dominated by shrubby roughleaf dogwood (Cornus drummondii) and elm (Ulmus spp.), but moderate
seed density (25-100 seeds/m2) in a grassland site
dominated by Kentucky bluegrass (Poa pratensis) and smooth brome (Bromus
inermis) . Seeds of sideoats grama were not encountered in the seed bank of a deciduous woodland
site dominated by tree-size roughleaf dogwood and elm.
Examination of Texas seed banks in plots managed with long-term (36-year) grazing Texas revealed seeds of
sideoats grama appeared to be transient and were not stored in seed banks.
grama was part of the historic vegetation: savanna dominated by
caespitose mid-grasses including sideoats grama, Texas tussockgrass (Nassella
Texas cupgrass (Eriochloa sericea), and little bluestem, with associated
short grasses including curlymesquite (Hilaria belangeri) and hairy
woolygrass (Erioneuron pilosum), and scattered clumps or
individuals of oak (Quercus spp.) and Ashe juniper
. Sideoats grama's cover was not
specified, although the authors did state late-seral mid-grasses had been
reduced by grazing. In a study testing seed viability in Kansas prairie
communities, soil samples taken from a mid-grass community dominated by sideoats
grama yielded only 2 sideoats grama germinants .
Seed dormancy can affect
timing of germination. Germination rate of sideoats grama seed from 148 sources ranged from 18% for the
most dormant seed to 96% for the least dormant . Major and Wright 
found after the postharvest period, dormancy was completely broken in sideoats
grama seed when floral parts were removed from caryopses. Germination was highest for seed with the
heaviest caryopses, and fewer caryopses per gram. Dormancy may be
controlled by "coumarin-like" inhibitory compounds.
A number of studies have
focused on germination requirements of sideoats grama. These studies reveal that
germination rates of sideoats grama vary with place of seed origin, as well as
with temperature regimes, moisture, and other conditions. Sideoats grama seed vigor is good
compared to seeds of other warm-season grasses . When conditions are
favorable, germination is rapid; in 1 case sideoats grama showed 50% germination
within 22 hours . Studies have
found differing results for germination success rate. Halinar  reported germination
rates of 20 to 30% and 18 to 34% in
2 consecutive years. Other sources found 50 to 70% germination
[40,68]. Jordan and Haferkamp  found high sideoats grama germination success, ranking 3rd out of 19 warm-season grasses tested. Wasser
 stated most sideoats grama seed germinates within 7 days under ideal
field conditions. Light improves germination .
Heat affects rate and success of sideoats grama germination. Temperatures
between 50 and 86 degrees Fahrenheit (10 and 30 °C) are generally best for germination [68,181]. Sabo
and others  found a constant temperature of 73
degrees Fahrenheit (23 °C),
or alternating temperatures of 54 degrees Fahrenheit (12 °C) for 8 hours with 88
degrees Fahrenheit (31 °C) for 16 hours, gave best
germination of sideoats grama. Over 1 month, germination of seed collected in southeastern
Montana averaged 95% for treatments of 68 to 86 degrees Fahrenheit (20 to 30 °C).
Seeds required 1 to 3 days to achieve 50%
germination. Germination for the
low-temperature treatment of 50 degrees Fahrenheit (10 °C) was only 60%, and
seeds required 15 days to attain 50% germination .
Jordan and Haferkamp  found the minimum
germination temperature for the 'NM-28' cultivar was 48 degrees Fahrenheit (8.9 °C).
also affects germination rate. Sideoats grama had the highest germination rate
(58%) at 1-inch planting
depth compared to 37% at 0.5 inch (12.7 mm),
10% at 2 inches, and 0% at 3 inches (76 mm) . Germination of sideoats grama
is good under both dry and moist conditions . Germination of sideoats grama
is "not greatly affected" by water stress down to 1 mP . Qi and Redmann ,
found sideoats grama had a lower tolerance to water stress than was reported in
Sabo and others , with 1 of the lowest germination rates of the 6 grass species tested
under water stress.
Seedling establishment/growth: Seedling
vigor of sideoats grama is good to excellent [86,212]. In a study comparing
seedling growth, sideoats grama seedlings developed more quickly than most of the 44
prairie forb and grass species tested . In the greenhouse, tillering began 3 weeks after seeds of sideoats grama were planted,
and continued at a rapid rate . Nine-week-old plants produced 20 to 40 stems and rhizomes. Temperature affected
seedling growth rate. Seedlings grew more rapidly at 80 to 85 degrees Fahrenheit (26.7 to
29.4 °C) than at 60 to 65 degrees Fahrenheit (15.5 to 18.3 °C)
. Of 5 grass species tested for growth patterns, 'Coronado' sideoats grama
showed the most rapid shoot and root growth .
Sideoats grama seedlings are more drought tolerant than many other
warm-season grasses, although seedlings that are not well established can be
killed by a short drought period . Dahl and others  found sideoats grama
was 1 of the easiest
species to establish in wet or dry years in Texas. Root length and root:shoot
ratio are important factors in survival rates of seedlings growing in
water-limited areas . In a study by Simanton and
Jordan , sideoats grama had the highest root length,
shoot length, and root:shoot ratio compared to other warm-season grass species. Robocker and others 
reported sideoats grama has high root growth in relation to leaf development.
Asexual regeneration: Sideoats grama
reproduces asexually from rhizomes and tillers.
Rhizomes are the main form of reproduction in Bouteloua curtipendula var.
curtipendula . The bunchgrass variety of sideoats grama (Bouteloua
curtipendula var. caespitosa) reproduces asexually from tillers.
Although rhizomatous, vegetative expansion of the 'El Reno' cultivar of sideoats grama studied in Colorado was primarily from
tillering. Rhizomes did not contribute significantly to new shoot production.
According to Sims and others  the 'El Reno' cultivar produced rhizomes mainly from reproductive
shoots and tillers mainly from vegetative shoots.
Sideoats grama occurs in all stages of succession. It is moderately shade tolerant , growing
in partial shade to full sun [36,136,183,212]. In ponderosa pine woodlands of
northwestern Nebraska, the importance of sideoats grama relative to other grass
species increases with increasing canopy cover, indicating that sideoats grama is relatively shade tolerant . Bolander  found sideoats grama
in Arizona chaparral was moderately dense where the canopy was open and grazing
was not been
Sideoats grama can be a primary or secondary colonizer on burned areas. Seeds
are carried into burned sites by wind or produced by plants surviving fire . Sideoats grama occurs in
early seral postfire communities  and increases on disturbed sites through
asexual regeneration or self-seeding [210,213]. Sideoats grama seeds more successfully on burned than unburned
sites [18,19], indicating it colonizes after disturbance by
fire. It may increase in cover immediately following fire [134,190], indicating it can
also spread by tillering or rhizome expansion. Leopold  described sideoats
grama communities maintained by frequent fires in areas relatively undisturbed
Sideoats grama is a climax indicator in arid grasslands throughout the
Southwest , and is a dominant or codominant species in late-seral
vegetation across much of the Great Plains . Dodd and Holtz  list
sideoats grama as a dominant component in late-seral grassland vegetation on a
loam range site in southern Texas.
Herbicides and fertilizer treatments:
Reaction of sideoats grama to
herbicide treatments varies with the herbicide and stage of phenological development. Sideoats grama had good to
excellent tolerance to imazethapyr
applied either pre- or postemergence . Application of 2,4-D favored establishment of sideoats grama
on an upland site seeded with native grasses and treated with 2,4-D, atrazine, and mowing
. In a study of the effects of clopyralid, picloram,
triclopyr, and 2,4,5-T, development of sideoats grama seedlings was reduced as
rate of herbicide application increased . Clopyralid had minimal effect at
application rates of 0.98 lb/ac (1.1kg/ha) and less, but the other 3 herbicides caused
more damage as application rate increased. Triclopyr and 2,4,5-T
had detrimental effects at 0.98 lb/ac (1.1kg/ha) or higher, and picloram caused increasingly
negative effects on growth at 1.96 lb/ac (2.2 kg/ha) and higher.
Application of fertilizer
may increase sideoats grama production. Application of nitrogen and nitrogen+phosphorus fertilizer increased
herbage production of sideoats grama
relative to the control on 3 different soil types in which laboratory
specimens were grown . On a loamy upland site in south-central New Mexico, cover of sideoats grama increased over
4 years with annual June application of nitrogen .
Light competition from trees may have detrimental effects on
sideoats grama stands. Sideoats grama increased after cabling of Colorado pinyon-oneseed
juniper woodland in south-central New Mexico . After trees, shrubs, and forbs in another pinyon-juniper
woodland were killed, herbage production for sideoats grama increased from 5 kg/ha 1 year after
treatment to 155 kg/ha 3 years after treatment . In eastern Nebraska native
little bluestem prairie, cover
of sideoats grama was lowest in shaded
plots under eastern redcedar, compared to plots
in open sites and at the edge of tree crowns . In contrast, McPherson and
Wright  found cover of sideoats grama increased
with increased canopy cover of redberry juniper on
both ungrazed and formerly grazed sites, even though overall grass production
decreased with greater canopy cover. In another study sideoats grama increased on plots where redberry
juniper was controlled with picloram .
Sideoats grama can reduce the success of other species. Sideoats grama in dense stands may reduce
honey mesquite (Prosopis glandulosa) seedling
establishment . Sideoats grama reduced dry mass of honey mesquite
when the 2 species were planted at the same time or when sideoats grama was already
established. Similarly, sideoats grama caused a decrease in the dry weight of
smooth hawthorn (Crataegus
laevigata) and sweet acacia (Acacia smallii) when planted with
those species .
Extracts from Utah juniper foliage and litter suppress growth of sideoats grama seedlings .
In grasslands, sideoats grama may be reduced by competition from taller prairie grasses more
adapted to mesic sites, declining in cover or disappearing from mesic
sites within a few years . Sideoats grama may have lower yield where planted with
tallgrass species, as taller grasses can outcompete sideoats grama .
Response to grazing pressure:
Sideoats grama is often considered an
increaser under grazing [6,90,113,162]; however, sideoats
grama often decreases under grazing on arid western ranges [20,24]. Tomanek and Albertson 
report sideoats grama both
decreased and increased under grazing, depending on site characteristics and
grazing pressure. Sideoats grama often increases under grazing in tallgrass
prairies [90,162]. When growing in association with little bluestem and blue
grama, sideoats grama often increases with
heavy grazing pressure but may be replaced
by blue grama or forbs . In Nebraska sideoats
grama increases under heavy grazing on favorable, wetter sites, but
does not do well under prolonged heavy grazing . Sideoats grama may increase under grazing due to
reduced competition by other
grasses. Percent species composition of sideoats grama declined from 11.54% to 1.12%
after 17 years of protection from grazing on a mixed-grass prairie in Nebraska
. On native prairie site in Kansas, a decrease in competition due to
drought caused an increase in relative cover and
seed production of sideoats grama until other grasses recovered . Sideoats
grama is most abundant on
steep slopes not easily accessible to cattle, and is increasing on some western
ranges protected from grazing [20,67]. Bolander  states sideoats grama
is common in areas of Arizona chaparral that have not been overgrazed, but is
replaced by other grasses in heavily grazed areas. Similarly, cover of sideoats grama in semiarid grasslands
of the Edwards Plateau in Texas has been
reduced by prolonged overgrazing .
Fire affects the response of sideoats grama to grazing. Sideoats grama increased in early spring-burned pastures
where fire essentially eliminated Kentucky bluegrass (Poa pratensis), increasing grazing
pressure on sideoats grama . Sideoats grama increased in cover and frequency in response to
bison grazing at stocking rates of 9 ha/AU
to 5 ha/AU ; the difference between grazed and ungrazed plots was significant (p < 0.1) on
tallgrass prairie sites burned every 4 years but was not significant on plots
burned annually. On season-long grazed sites, moderately stocked (3.3 ac/head)
with cattle, sideoats grama represented a greater proportion of vegetation composition on
spring-burned plots than on unburned plots monitored from
1950 to 1967 . Sideoats grama significantly (p< 0.05) increased in percent
species composition 4 years after fire on sites under season-long
continuous grazing and fertilized with 80 lb/ac (90 kg/ha) nitrogen, but decreased
(though change not significant at p = 0.05) on unburned, grazed plots fertilized at 80 lb/ac nitrogen . For more information about the response of sideoats grama to
fire, see Fire Effects.
Sideoats grama establishes quickly and provides good erosion control
. It is commonly seeded on southern plains ranges to reduce wind erosion,
reduce soil temperatures and evaporation, and help control weeds
. Sideoats grama is very drought resistant [3,113,153,213],. Density and
vigor of sideoats grama stands may decrease during drought ; however, stand density
may increase, and sideoats grama expand by self-seeding, after drought .
Sideoats grama can increase rapidly on prairie damaged by extreme drought or overgrazing .
and seeding rate: Seed weight for sideoats grama is
170,000 seeds/lb  to 191,000 seeds/lb [44,192]. Range of pure live seed (PLS) per pound of bulk seed was
reported as 42,020 to 64,940 PLS/lb bulk . Recommended seeding rate is 3 to 6 lbs PLS/ac
(3.3 to 6.7 kg/ha).
Seeding dates vary from April 1 to May 15 in the northern and central Great
Plains, January to April in the southern Great Plains and June 15 to July 15 for
Trans-Pecos Texas and the Southwest .
Sideoats grama is often included in native seed mixes for prairie reclamation
[5,78] and is widely used for reseeding
ranges . Stubbendieck and others  recommend sideoats grama as a
component of native grass mixes in silty, clayey, and sandy sites throughout
Nebraska. Sideoats grama is used for revegetating coal surface-mined lands in the eastern
, Iowa , eastern Montana , and other areas. It
has been seeded successfully on iron ore for mine reclamation in Wisconsin .
Cultivars: Sideoats grama is commercially available . Several improved cultivars of sideoats
grama have been developed including 'Vaughn' and 'Niner,' originating from western
areas of the Southwest , 'Trailway' from Nebraska, 'Pierre' from
South Dakota, 'Kildeer' from North Dakota, 'Premier' and 'Haskell' from
Texas, as well as 'EL Reno,' 'Butte,' and 'Native' [97,156,186]. Production and
timing of maturity of the individual cultivars vary by planting
site . Improved cultivars are often used for reclamation. Of several cultivars
evaluated at a mine site in the Southwest, 'Vaughn' ranked best for both stand
density and vigor in all 3 study years, followed by 'NM-28' and 'El Reno'
The scientific name of sideoats grama is Bouteloua curtipendula
(Michx.) Torr. (Poaceae) [49,73,78,91,104,105,128,217]. Recognized varieties are as follows
Bouteloua curtipendula var. caespitosa Gould & Kapadia
B. curtipendula var. curtipendula (Michx.) Torr.
Most sources reviewed in this species summary do not distinguish between varieties, but pertain to areas within
the range of Bouteloua curtipendula var. curtipendula
(see Distribution and Occurrence).
Where information presented in this summary pertains to a particular variety,
the variety will be specified as either B. curtipendula var. curtipendula
or B. curtipendula var. caespitosa.