General: Bunchgrass is the general name for perennial grass species that tend to grow in
discrete tufts or clumps (i.e., bunches) rather than in sod-like
carpets. Bunchgrass tend to have deep roots and can get moisture from
the soil when shallow-rooted sod-like grasses would dry out. There are
many species of bunchgrass around Las Vegas, a few of which are easy to
recognize, but to the casual observer, it is sufficient to recognize
bunchgrasses as different from "carpet" grasses and
from Sedges (e.g., Scirpus spp.) and Rushes (e.g., Juncus spp.):
Sedges [sedge stems] have edges,
Rushes [rush stems] are round,
And Grasses have leaves all the way to the ground.
Experts use various characteristics of the flowers and seeds to identify individual species.
Native Bunchgrasses are a good indicator of the health
of desert vegetation communities. Most of the desert has been grazed by
cattle, horses, burros, or sheep during historic times, and herds of
these animals tend to overgraze bunchgrasses to near extirpation. Thus,
if bunchgrasses are present, the vegetation community probably has
never been overgrazed and probably is healthy.
Bunchgrasses are common components of vegetation associations in the Upper Sonoran
(Mojave Desert Scrub and Pinyon-Juniper Woodland), Transition
(Yellow Pine Forest), and Canadian
life zones except in areas overgrazed by cattle. Bunchgrasses can also be found at higher and lower elevations, but in smaller numbers.
Family: Grass (Poaceae).
Other Names: Each species has at least one name.
Plant Form: Grass; growing upright in bunches.
Height: Leaves usually to about shin-high; seed stalks to about thigh-high.
Stem: Usually round, hollow.
Leaves: Long and narrow, like grasses.
Flowers: Inflorescence is a panicle; branchlets upright on stalk to drooping in bunches. Flowers tiny.
Seeds: Achene-like grain (like small sunflower seeds).
Habitat: Most desert habitats from the low desert to the high mountains.
Elevation: To 10,000+ ft
Comments: There are many species of grass, spread across many genera, that exhibit the bunchgrass life form. Some common
species of bunchgrass that are fairly easy to identify are listed below.
Indian Ricegrass (Achnatherum hymenoides [Oryzopsis hymenoides]) is a
stately bunchgrass that
grows to about 2 feet and has a wide, open mass of branched flower
stalks. The many seeds are relatively large and rice-like. Native
peoples and pioneers harvested the seeds. Ricegrass tends to grow in
sandy soils at elevations below about 6,500 ft.
Desert Needlegrass (Achnatherum speciosum [Stipa speciosa]).
Desert Needlegrass is a large bunchgrass that grows to about 2-feet
tall and 2-feet wide. There are many seed stalks per plant, each with a
4-inch-long, tight panicle of flowers. The long awns attached to the
seeds are twisted and sharply bent at the middle. Desert Needlegrass
tends to grow in rocky soils and washes at elevations below about 7,000
Fluffgrass (Dasyochloa pulchella).
Fluffgrass is a small bunchgrass that only grows 4-6 inches tall. The
leaves are short, and the seed stalks barely stand above the leaves.
The flower spikelets are covered in silvery hairs, giving the plant a
fluffy white appearance. Fluffgrass grows in sandy and rocky soils at
elevations of about 1,000 to 5,500 feet.
Big Galleta Grass (Pleuraphis rigida [Hilaria rigida]).
Big Galleta Grass is a big bunchgrass that grows to about 3.5-feet
tall. Leaves are long and narrow. Stems grow erect with long (to 6
inches), open seedheads. The 0.5-inch-long spikelets radiate from the
end of the spike. Big Galleta Grass grows on sandy and rocky soils at
elevations below about 5,000 feet.