Description: This introduced perennial grass is 3-6'
tall at maturity. It consists of a dense tuft of basal leaves from low
vegetative shoots and slender culms with a few alternate leaves; each culm
terminates in an inflorescence on a long naked stalk. The culms are light
green, terete, and glabrous; later they become
straw-colored.
Both the basal and cauline leaves have a similar appearance. Their blades are
up to 10" long, 1/3" across, green, and hairless. The blades of the basal
leaves spread outward, while the blades of the cauline leaves spread outward
and then droop toward their tips. The leaf sheaths are dull light green and
hairless; they have longitudinal veins. The ligules have long papery membranes
that become more or less shredded. The inflorescence consists of a panicle of
spikelets; the branching pattern of this panicle tends to occur along a
2-dimensional plane. The panicle is up to 8" long and consists of a few short
branches that are stiff and ascending. Each branch has a dense tuft of
spikelets along it upper half, otherwise it is naked. While the flowers are
blooming and shortly afterwards, this panicle may span up to 4" across;
however, both before and afterwards, it is more narrow. Each spikelet consists
of a dense tuft of 3-7 florets and their lemmas; there is pair of glumes at the
bottom. The spikelets are whitish green while their florets are blooming, but
they later become tan, brown, or nearly white. The glumes are
linear-lanceolate, keeled, and unequal in size; the shorter glume of a pair is
about 5 mm. in length, while the longer glume is about 6 mm. in length. The
lemmas are linear-lanceolate and ciliate along their keels; they are about 5-8
mm. in length. In each spikelet, the upper lemmas tend to be shorter than the
lower lemmas. Each floret has a pair of white plumose styles and 3 stamens with
large white anthers. The blooming period occurs from late spring to mid-summer.
Pollination is by wind. The root system consists of short rhizomes and fibrous
roots.
Cultivation: The preference
is partial sun, mesic conditions, and a fertile soil consisting of loam or
clay-loam. This robust grass also grows readily in full sun and moist or
slightly dry conditions. It is rather aggressive, but doesn't tolerate regular
mowing.
Range & Habitat: This
common grass occurs in every county of Illinois (see
Distribution
Map). It was introduced from Europe as a source of hay and pasturage.
Habitats include savannas, woodland borders, thickets, disturbed meadows in
wooded areas, powerline clearances in wooded areas, fence rows, old fields and
pastures, orchards, and miscellaneous waste areas. Areas with a history of
disturbance are preferred.
Faunal
Associations: The caterpillars of the moth Leucania
multilinea (Many-Lined Wainscot) and the butterfly Megisto cymela
(Little Wood Satyr) feed on the foliage of this grass. Its seeds are eaten
sparingly by some granivorous songbirds, including the Horned Lark and Chipping
Sparrow. Hoofed mammalian herbivores (primarily livestock) graze on Orchard
Grass. The foliage provides cover for small mammals.
Photographic Location: A powerline clearance at
Busey Woods in Urbana, Illinois. The upper photograph shows the appearance of
the spikelets after the blooming period, but before the grains are
mature.
Comments: Orchard Grass
develops early and becomes tall; it usually blooms by early summer. At this
time of year, it can be identified by the stiff lower branches of the panicles;
each of these lower branches form an angle of 90° or less with the central
axis of the inflorescence. Furthermore, each branch has a dense tuft of
spikelets along its upper half, otherwise it is naked. Both the glumes and
lemmas are rather long (5-8 mm.) and they are usually ciliate along their
keels. The foliage of Orchard Grass is hairless and the ligules have long
papery membrances that are often shredded. These various characteristics are
especially useful in identifying this species correctly. Orchard Grass is the
only Dactylis sp. in Illinois.