Description: This native perennial grass
is 2½–5' tall; it is often tufted at the base, sending up multiple
culms from short rootstocks. The light to medium green culms are unbranched,
stiffly erect, terete, rather stout, and glabrous. Each culm has about 5-7
alternate leaves; most of these leaves are located along the lower half of each
culm. The medium green leaf blades are up to 2' long and 4.5 mm. across; they
are ascending to widely spreading with long slender tips. Each leaf blade is
rough along its margins and underside, and slightly indented/keeled along its
middle. Near the base of each leaf blade, there are long white hairs on the
upper surface, otherwise it is hairless. The leaf sheaths are medium green,
hairless, and longitudinally veined. The ligules are ciliate, while the nodes
are mostly hidden by the sheaths and insignificant. Each culm terminates in a
spike-like panicle about 4-10" long. This narrow panicle is mostly hidden by
the uppermost sheath when it is young, but becomes more exposed at maturity.
The short branches of the panicle are erect throughout. The individual
spikelets of the panicle are 4.5–6.0 mm. long and 1.25 mm. across; they
are often organized into groups of 2-3 on the branches, and their pedicels are
short. Immature spikelets are white, but they become purplish green and
glabrous with age. Each spikelet consists of a pair of glumes, a single lemma,
and a palea enclosing the perfect floret. The glumes are unequal in size: the
shorter glume is 2.0–3.0 mm. long, while the longer glume is 3.0–4.0
mm. long. The lemma and the palea are about equal in size (4.0–6.0 mm.)
and longer than either glume. The blooming period occurs from early to
mid-fall. Afterwards, the spikelets become light tan when their grains are
ripe; disarticulation is above the glumes. The root system is
fibrous.
Cultivation: The preference
is full sun and mesic to dry conditions. Practically any kind of soil is
tolerated, including those containing rich loam, clay-loam, sand, or gravelly
material. This grass species has excellent drought tolerance because of its C4
metabolism.
Range & Habitat:
Tall Dropseed is occasional in most areas of Illinois (see
Distribution
Map). Habitats include black soil prairies, sand prairies, typical savannas
and sandy savannas, open woodlands in rocky upland areas, limestone glades,
areas along railroads, and roadsides. This species is typically found in
dry-mesic railroad prairies of variable quality. While such prairies have
declined because of the invasion of woody vegetation, this species has managed
to adapt to adjacent disturbed areas that remain open and sunny.
Faunal Associations: Several species of grasshoppers
feed on the foliage of Tall Dropseed (see
Grasshopper Table);
this prairie grass is one of the preferred food plants of Eritettix
simplex (Velvet-Striped Grasshopper), Orphulella speciosa
(Slantfaced Pasture Grasshopper), and Syrbula admirabilis (Handsome
Grasshopper). Grasshoppers are an important source of food for many
insectivorous songbirds and upland gamebirds. The seeds of Sporobolus
spp. (Dropseed grasses) are eaten by some granivorous songbirds,
particularly during the winter. These species include the Slate-Colored Junco,
Lapland Longspur, Smith Longspur, Field Sparrow, White-Crowned Sparrow, and
others. Some upland gamebirds probably eat the seeds as well. The Prairie Vole
eats both the seeds and foliage of Tall Dropseed. Some hoofed mammalian
herbivores, such as bison and cattle, graze on the foliage of this and other
Dropseed grasses, particularly when it is immature.
Photographic Location: A prairie remnant along a
railroad just north of Champaign, Illinois.
Comments: This is the forgotten grass of the
tallgrass prairie. While Tall Dropseed is not one of the dominant grasses of
this ecosystem, it is about as common as Sporobolus heterolepis (Prairie
Dropseed). Even though they belong to the same genus, Tall Dropseed doesn't
closely resemble the latter species, which has a long-stalked spreading
inflorescence. In contrast, Tall Dropseed has a closed inflorescence that is
only partially exerted from the uppermost sheath. Other species in this genus
that have closed inflorescences are either smaller annual species (e.g.,
Sporobolus vaginiflorus & Sporobolus neglectus), or their
inflorescences are fully exerted from the uppermost sheath (e.g., Sporobolus
clandestinus). Tall Dropseed should be used in prairie restorations more
often than it is.