Grass family (Poaceae)
This grass is a spring annual that develops either individual or tufted leafy culms about
1½-3' tall. The hollow culms are light green, glabrous, and terete;
they are largely hidden by the sheaths. A few alternate leaves occur
along the entire length of each culm. The blades of these leaves are up
to 15 mm. across and 12" long; both the blades and the sheaths are
medium green to blue-green, glabrous, and sometimes glaucous. The
ligules are white-membranous. Each culm terminates in a panicle of
spikelets about 4-10" long. The lateral branches of the panicle occur
in whorls of 2-5 along its central stalk (rachis). These lateral
branches divide into whorls of pedicels that terminate in
individual nodding spikelets. Some whorled pedicels are attached to the
upper half of the central stalk. Each spikelet consists of a pair of
glumes about ¾-1" in length, a pair of lemmas about ½-¾" in length, and
their florets. Both the glumes and lemmas are light green, elliptic in
shape, and convex along their outer surfaces. The glumes have 7-11
prominent longitudinal veins, while the veins of the lemmas are more
obscure. Usually the lemmas are awnless, otherwise they have fairly
straight awns up to 1¼" in length. In each spikelet, the lemmas are
largely hidden by the glumes. Each floret has 3 anthers and a pair of
feathery stigmata. The blooming period occurs from late spring to
mid-summer and lasts 1-2 weeks. The florets are either cross-pollinated
by the wind or self-fertile. The florets of the lemmas develop into
ripened grains later in the summer or fall. These grains are narrowly
ellipsoid and narrowly furrowed along one side; they are a little
shorter than the lemmas. The root system is shallow and fibrous.
Oats will adapt to full sun, moist to dry conditions, and either barren
or fertile soil containing loam, clay, gravel, etc. It develops quickly
during the cool moist weather of spring.
Habitat: Oats naturalizes occasionally throughout
although it rarely persists for more than a few generations (see Distribution Map).
non-native grass was introduced from Europe into North America for
agricultural purposes. Habitats consist of cropland, abandoned fields,
roadsides, areas along railroads, and areas near grain elevators.
Highly disturbed habitats with exposed open ground are preferred. Oats
is still cultivated as a source of grain, forage, and straw. It is also
used for erosion-control purposes along roadsides and others areas.
Associations: Various insects feed on oats (Avena sativa).
species include the caterpillars of such moths as Agrotis venerabilis
(Venerable Dart), Apamea
sordens (Rustic Shoulder-Knot), and Xestia
c-nigrum (Lesser Black-Letter Dart). Other insect feeders
(Toothed Flea Beetle), Chaetocnema
(Corn Flea Beetle), Diabrotica
barberi (Northern Corn Rootworm), Oulema
melanopus (Cereal Leaf Beetle), and Sphenophorus maidis
femurrubrum (Red-Legged Grasshopper) and
(Migratory Grasshopper); Aphis
(Erigeron Root Aphid), Forda
padi (Cherry/Oat Aphid), Schizaphis gramineum
(Greenbug), and Sitobion
avenae (English Grain Aphid); and the plant bug Trigonotylus
ruficornis. Many upland gamebirds and granivorous
songbirds eat the
seeds of oats (see Bird Table), while the Canada Goose consumes both
the foliage and seedheads.
Both the foliage and seeds of oats are occasionally used to feed
domesticated farm animals, particularly horses. For a grass species,
the seeds of oats have relatively high protein content.
Location: A field in Urbana, Illinois.
Because of its large distinctive spikelets, Oats is fairly easy to
identify as a grass. It superficially resembles one of the Brome
grasses (Bromus spp.),
but the spikelets of the latter have more lemmas
that are plainly visible above the glumes. Another introduced grass
that is slightly more weedy, Wild Oats (Avena fatua), also
Illinois. It is similar in appearance to the cultivated Oats that is
described here. Wild Oats can be distinguished by its pubescent lemmas,
crooked awns of its lemmas, and more narrow leaf blades (less than 10 mm.