BOTANICAL AND ECOLOGICAL CHARACTERISTICS
SPECIES: Bouteloua curtipendula | Sideoats Grama 



GENERAL BOTANICAL CHARACTERISTICS : 
Sideoats grama is a widepread, perennial, warm-season native midgrass
[32].  It most commonly occurs in tufts or in small bunches, forming
open patches [15,37].

Both rhizomatous and nonrhizomatous bunchgrass varieties (or forms
according to some authorities) occur [6,43].  Rhizomes are scaly and
from 2 to 5 inches (5-13 cm) in length [14,36].  Sideoats grama reseeds
readily when sufficient water is available [30,37].

Sideoats grama, sometimes called "tall grama," is the largest species of
grama and reaches from 0.66 to 3.3 feet (0.2-1.0 m) in height [32,37].
The slender culms are erect and smooth, with a purple tint at the nodes
[14,32].  Leaves or blades are mostly flat, although somewhat involute
at the tip, and have hairy margins [6,37].  The inflorescence is made up
of 20 to 60 spikes which hang on one side of the slender flower stalk
[34,37].

Sideoats grama is relatively drought resistant; roots are well adapted
to growth in dry conditions [37].  Sideoats grama typically has many
coarse, fibrous roots [34].  Roots can grow to 2 to 4 feet (0.6-1.2 m)
in length and can spread laterally 1 to 1.5 feet (0.3-0.5 m) in the top
2 to 4 inches (5-10 cm) of soil [37].  When the subsurface soil is wet,
sideoats grama rapidly extends its seminal root into the subsurface
level, thus reducing dependency on the changeable moisture levels of the
upper soil zone [30].  Sideoats often increases dramatically after
drought [33,37].

In a Nebraska study, sideoats grama was found to have an average of 170
to 423 roots per plant [38].  The same study revealed 0 percent root
mortality after 1 year, 64 percent after 2 years, and 84 percent after 3
years [38].  Other researchers have reported that individual plants on
ungrazed sites can live for up to 7 years, although most die within the
first few years [4].


RAUNKIAER LIFE FORM : 
   Hemicryptophyte
   Geophyte


REGENERATION PROCESSES : 
Sideoats grama reproduces by seed, rhizomes, and tillering or lateral
spread [32].  It produces a fair amount of low viability seed [34], but
it reseeds readily when adequate moisture is available [37].

A number of studies have focused on germination characteristics of
sideoats grama.  When conditions are favorable, germination is rapid,
with 50 percent germination within 22 hours [30].  Evidence suggests
that many seeds germinate during important longer wet periods.  If the
wet periods are too short, most seeds cannot germinate but do survive as
viable seed [10].  Even when a high percentage of seeds germinate,
seedlings may be insufficiently developed to survive a short drought
period [10].  Seedling vigor is reported to be good in comparison with
other native warm-season grasses [35].

Establishment appears to be more successful when rains occur later in
the summer [10].  Seedling establishment and survival can also be
influenced by grazing.  In a southern Arizona study, establishment was
less successful on grazed ranges, but seedling survival was actually
somewhat higher on grazed sites [4].  Results were as follows [4]:

         Annual Number of New Plants           Survival of Seedlings
         per meter square                      During 1st Growing Season-%
Grazed              3.9                                  46.6 
Ungrazed            5.0                                  33.9

Both rhizomatous and nonrhizomatous or bunchgrass type varieties (or
forms) of sideoats grama occur.  Rhizomatous sideoats grama produces
short 2 to 4 inches (5-10 cm), slender, scaly rhizomes that form thick
mats [14,16,37].  Rootstock spreading is the main form of reproduction
in rhizomatous sideoats grama [34].


SITE CHARACTERISTICS : 
Sideoats grama is widely distributed across the plains, prairies, and
lower mountains of much of North America [14,15].  It grows abundantly
on lower elevation mesas and canyons, scablands, weedy meadows, open
woodland hillsides, and on steep rocky slopes [6,16,44].  Sideoats grama
is described as most abundant and important in the central and southern
mixed prairie [37].

Sideoats grama occurs on a variety of soils including sandy,
clay-textured soils with a relatively high pH, and rocky, alkaline soils
relatively high in available nitrate and low in available water [24].
It grows abundantly on the rough soil of breaks and on light soils [37].
Sideoats grama is drought tolerant and often becomes abundant following
prolonged dry periods [37].

Sideoats grama typically grows in tufts or small bunches intermixed with
other species [33].  It commonly occurs with species such as the
bluestems (Andropogon spp.), Idaho fescue, prairie junegrass, blue
grama, little bluestem, threadleaf sedge (Carex filifolia), western
wheatgrass, bluebunch wheatgrass, skunkbush sumac (Rhus trilobata),
black greasewood, Rocky Mountain juniper, and ponderosa pine.  In some
areas sideoats grama grows in dense, nearly pure stands with substantial
litter accumulation [3].

Elevational ranges for sideoats grama are as follows [8]:

            from:  3,500 to 7,500 feet (1,068-2,250 m) in CO
                   3,100 to 4,000 feet (946-1,220 m) in MT
                   4,900 to 6,200 feet (1,495-1,891 m) in UT
                   4,000 to 5,000 feet (1,220-1,525 m) in WY



SUCCESSIONAL STATUS : 
Obligate Climax Species

Sideoats grama is a climax dominant or codominant across much of the
Great Plains [12].  Depending on the type and severity of disturbance,
it can also occur in some seral communities.  Sideoats grama often
increases abundantly following drought [33,37].


SEASONAL DEVELOPMENT : 
Sideoats grama begins annual growth in the early spring.  Development is
generally rapid; plants reach 1.5 to 2 feet (0.5-0.6 m) in height by
summer [37].  Flower stalks first appear in late June or early July;
flowering continues into August or September [12,37].  Flowering dates
in selected states are as follows [8]:

           Beginning of Flowering           End of Flowering

  CO              July                          September
  MT              July                          August
  ND              July                          August
  WY              July                          September

Sideoats grama typically remains green late in the season [37].

Related categories for Species: Bouteloua curtipendula | Sideoats Grama