Description: This native perennial grass is 3-7'
tall and unbranched. It typically consists of tight bunches of flowering culms
and their leaves. The culms are terete, glabrous, and light green to pale
yellow. The blades of the alternate leaves are up to 2' long and ½"
across; they are dull green to dark green, flat, and hairless.
The
blade of each leaf ascends upward from the culm and spreads outward towards its
tip. The leaf sheaths are dull green, hairless, and open. The nodes of the
culms are slightly swollen, dark-colored, and covered with fine silky hairs (at
least when they are young). Most of the leaves are located along the lower
halves of the culms. Each culm terminates in a narrow panicle of floral
spikelets. This panicle is up to 14" long and it has several ascending
branchlets that are individually up to 4" long. The branchlets are some shade
of golden brown or tan, mostly glabrous, and slender. However, the tips of the
branchlets underneath the spikelets usually have fine silky hairs. Each
branchlet terminates in a one-flowered spikelet about 1/4" (6 mm.) to 1/3" (8
mm.) long. This spikelet consists of a pair of appressed glumes and a pair of
membranous lemmas within. The glumes are about the same length as the spikelet;
they are golden brown to tan, lanceolate, gently curved, and somewhat shiny.
One glume is covered with silky white hairs, while the other glume is mostly
hairless. The fertile lemma has a long awn at its tip that is often bent,
curly, or twisted; this awn is about ½" in length. At the base of each
spikelet, there is an obsolescent pedicel up to ¼" long; this pedicel is
covered with silky hairs and it lacks a spikelet at its apex. The floret of
each spikelet has 3 stamens with yellow to brown anthers and 2 stigmas that are
white and plumose. The blooming period occurs during late summer to early fall.
At this time, the branchlets of the panicle spread outward slightly;
afterwards, they become more appressed and ascending. The root system is
fibrous and has short rhizomes.
Cultivation: The preference is full to partial sun
and slightly moist to dry conditions. Various kinds of soil are tolerated,
including those that can loam, clay-loam, sand, and gravel. Most growth and
development occurs during the warm weather of summer because of the C4
metabolism of this grass. It can spread aggressively in some situations (e.g.,
prairie restorations).
Range &
Habitat: This common grass can be found in every county of Illinois
(see
Distribution
Map). It was one of the dominant grasses of the prairies that covered much
of Illinois during historical times. Habitats include savannas and sandy
savannas, black soil prairies, clay prairies, sand prairies, gravel prairies,
dolomite prairies, hill prairies, cemetery prairies, barrens with scrubby
vegetation, limestone glades, grassy fens, fallow fields, roadsides, and areas
along railroads (particularly where prairie remnants occur). Indian Grass is
often used in tallgrass prairie restorations.
Faunal Associations: Several species of grasshoppers
feed on the foliage of Indian Grass (see
Grasshopper Table);
these grasshoppers are an important source of food to many insectivorous
songbirds and upland gamebirds. Other insects that feed on this prairie grass
include the leafhopper Flexamia reflexus, the planthopper Myndus
fulvus, the Issid planthopper Bruchomorpha extensa, and the
caterpillars of Amblyscirtes hegon (Pepper-and-Salt Skipper). The
foliage is also palatable to hoofed mammalian herbivores, including bison and
cattle. Because of its height and tendency to remain erect, it provides good
cover for many kinds of birds and animals in prairies.
Photographic
Location: A restored prairie at Meadowbrook Park in Urbana,
Illinois. In the upper photograph, Andropogon gerardii (Big Bluestem) is
the tall grass in the background.
Comments: This tall prairie grass is attractive,
particularly while the florets are blooming. It remains erect throughout the
summer and even during the winter. Another dominant prairie grass,
Andropogon gerardii (Big Bluestem), is more likely to lean in the
direction of the prevailing winds, and its culms topple over during the winter
to smother surrounding vegetation. Indian Grass is easy to identify because of
its height and distinctive golden-colored inflorescence. It is distantly
related to Sorghum spp. (Sorghums) of the Old World, including the
introduced Sorghum halepense (Johnson Grass). However, the spikelets of
Sorghums occur in pairs (one sessile, the other pedicellate). Indian Grass and
other Sorghastrum spp. have pairs of sessile spikelets and empty
pedicels; these pedicels lack spikelets. Other Sorghastrum spp., which
occur primarily in the southeastern states, have spikelets with awns at least
¾" long. In contrast, Indian Grass has awns that are less than ¾"
long.