This grass is a perennial or annual (depending on the climate), forming
a loose tuft of leafy culms about 2-3' tall. These culms are erect or
ascending; they are light green to light reddish green, terete, and
glabrous; sometimes they branch from the axils of lower leaves. Along
each culm, there are 3-6 alternate leaves. The leaf blades are 4-9"
long and 4-15 mm. across; they are ascending to widely spreading, flat
or slightly involute (folded upward along the margins), medium green,
and glabrous to minutely pubescent. The blade margins are scabrous
(rough-textured). The leaf sheaths are open, medium green, vertically
veined, and glabrous to minutely pubescent. The ligules have short
hairs (about 1 mm. in length), while the nodes are light green,
slightly swollen, and glabrous. Each culm (and any lateral culms)
terminates in an inflorescence consisting of a rachis with 3-10
spike-like racemes; these racemes are arranged along one side of
the rachis. The rachis of this inflorescence is 3-6" long and about 1
mm. across or slightly more; it is angular and densely villous (covered
with long soft hairs). Relative to this rachis, the spike-like racemes
are ascending; each successive raceme becomes progressively shorter
(½–3" in length).
Each raceme has a secondary rachis above and 2 rows of
partially overlapping spikelets below. The spikelets have short
pedicels (about 0.5 mm. in length) that are densely villous. Relative
to their secondary rachises, these spikelets are ascending. The
secondary rachises themselves are angular and densely villous. Each
spikelet is 4.5–5 mm. long, about 2.5–3 mm. across, and
single-flowered; it is broadly ellipsoid and slightly flattened in
shape. Each spikelet has an outer glume, a sterile outer lemma, a
fertile inner lemma with a perfect floret, and a small callus at its
base. Both the outer glume and outer lemma are the same length as the
spikelet; they are broadly elliptic in shape, convex along their outer
surfaces, light green, 5-veined, and glabrous to sparsely
short-pubescent. The inner lemma is about 3.5–4.5 mm. in length and
hardened. The blooming period occurs from mid-summer to early autumn.
The florets are cross-pollinated by the wind. Afterwards, individual
spikelets disarticulate below their glumes as they become mature. The
grains of these spikelets are 3–4 mm. long, broadly ellipsoid in
shape, and partially flattened along one side. The root system is
fibrous. This grass reproduces by reseeding itself.
The preference is full or partial sun, more or less mesic conditions,
and fertile loamy soil. In Illinois, this grass is an annual. Growth
and development begins after danger of hard frost during the spring,
and continues through the summer. Because this grass has a C4
metabolism, it is able to withstand periods of hot dry weather. It is
Hairy Cup Grass has been found
primarily in NE Illinois
and scattered counties elsewhere (see Distribution
This grass is
uncommon in Illinois, although it may be spreading. It is native to
Eurasia, its range extending from eastern Europe to Japan. Hairy Cup
Grass was probably introduced into North America from contaminated
shipments of grain or by other accidental means. In the Midwestern
states, this grass has become more common during the past 20 years and
it appears to be spreading. Habitats consist of cropland (primarily
corn fields) and roadsides. This grass was also found along the edge of
a prairie restoration in Urbana, Illinois. Habitats with a history of
disturbance are preferred.
At the present
time, little is known about floral-faunal relationships for this
non-native grass in North America. Hairy Cup Grass (Eriochloa villosa
is listed as one of the host plants for the caterpillars of a
polyphagous moth, the Stalk Borer (Papaipema
); see Rice
Davis (2010). The grains of this grass are consumed by some species of
) and ground beetles (e.g. Harpalus pensylvanicus
granivorous songbirds and rodents also feed on the grains (Simard et
al., 2013). Agricultural machinery and vehicles probably spread the
grains to new locations.
The specimen was
collected from the edge of a prairie restoration in Urbana, Illinois.
It was photographed indoors.
This non-native grass is
a relatively recent introduction into Illinois. Other cup grasses
in Illinois are adventive from the Great Plains and
western states, and they are also uncommon within the state. Hairy Cup
Grass (Eriochloa villosa
can be distinguished from other cup grasses
within the state by its stouter spikelets and villous rachises and
pedicels. It also resembles some species of native bead grass (Paspalum
), however its racemes of spikelets occur along only
one side of the primary rachis, rather than two sides, and its
rachises and pedicels are more villous (covered with long soft hairs).
Another common name of this grass is Woolly Cup Grass.