Grass family (Poaceae)
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.