Description: This native grass is a short-lived perennial about 2' tall and unbranched. It forms tufts of leaves from vegetative shoots and produces flowering culms (stems). Each culm is green, slender, and round in cross-section; it is either glabrous, sparsely hairy, or slightly pubescent. The nodes of the culms are usually pubescent as well. Each culm has 3-5 alternate leaves along its length at flowering time. The blade of each cauline leaf is up to 6" long and 1/3" across (or slightly larger); it is greyish blue, linear to broadly linear, and flat or rolled upward along the margins. The upper surface of each leaf blade is mostly hairless, although long hairs are often present near its margins or along the central vein of its underside. The margins of the leaf blade are smooth in appearance, but rough to the touch. Each leaf has an open sheath that is greyish blue and usually quite hairy or pubescent.
Each culm terminates in an open panicle
of spikelets up to 6" long. The weight of the individual spikelets on their
slender pedicels causes the entire panicle to droop sideways and downward. Each
spikelet is up to 1" long and consists of up to 5 pairs of stacked lemmas and a
pair of glumes at the bottom; there is usually a single lemma at the apex of
the spikelet. The glumes are about 1/4" in length, linear in shape, and
awnless; the short-awned lemmas are about 1/3" in length and linear-lanceolate.
Both glumes and lemmas have multiple raised veins along their sides and they
are both silky hairy or silky pubescent. The blooming period occurs during
early summer. After the blooming period, the spikelets change color from silky
light green to a dull light brown. The root system consists of short rhizomes
and fibrous roots.
Cultivation: The
preference is full or partial sun, moist to slightly dry conditions, and a
loam, clay-loam, or gravelly soil with an average to above-average pH. This
plant is easy to grow, but it can be short-lived. Most vegetative growth occurs
early in the year (from mid-spring to early summer).
Range & Habitat: Prairie Brome is an uncommon
plant in central and northern Illinois, while in southern Illinois it is
largely absent (see
Distribution
Map). Habitats include mesic to dry prairie remnants and grassy fens. This
conservative species is rarely found in degraded habitats. In prairies, it
becomes one of the understory grasses later in the year.
Faunal Associations: The foliage of Bromus
spp. (Brome Grasses) is eaten by Phoetaliotes nebrascensis
(Large-headed Grasshopper), the caterpillars of the moth Leucania
multilinea (Many-Lined Wainscot), and other insects. It is suspected that
the seeds of Brome Grasses are eaten by Aelia americana (Stink Bug sp.).
The rather large seeds of Brome Grasses are eaten by various upland gamebirds,
sparrows, and small rodents (ground squirrels, mice), while the foliage is
grazed by rabbits, deer, and elk.
Photographic
Location: The wildflower garden of the webmaster in Urbana,
Illinois.
Comments: This is the only
native Bromus sp. (Brome Grass) that can be found in Illinois prairies.
The other native Bromes occur in or near woodlands. In general, this genus is
dominated by weedy annual grasses that have been introduced from Eurasia –
they are often seen along roadsides, railroad tracks, fields, and waste areas.
Prairie Brome is an attractive grass that remains fairly short; it has greyish
blue leaves and a nodding inflorescence that changes color as it matures.
Prairie Brome can be distinguished from other Bromus spp. (Brome
Grasses) by considering the following characteristics: 1) It is more hairy than
most Brome Grasses, especially on the surface of its sheaths and spikelets, 2)
Each of its culms has only 3-5 alternate leaves, while many other Brome Grasses
have more cauline leaves than this, 3) The glumes and lemmas have several
raised veins along their sides (about 3 for each glume and 5-7 for each lemma),
while the glumes and lemmas of other Brome Grasses have fewer such veins or
lack them altogether, and 4) The lemmas of Prairie Brome have short awns (2 mm.
or less in length), while many other Brome Grasses have lemmas with longer awns
(exceeding 2 mm. in length) or they lack awns
altogether.