Description: This native perennial grass is 6-16' tall and unbranched; individual plants are erect or they may lean over with age. The culm is light green, hairless, and rather stout; it has small rectangular impressions across its surface. The alternate leaves are abundant along the culm and they are ascending. The leaf blades are up to 2' long and 2" across; they are light green or greyish blue, linear-lanceolate, and hairless. The upper surface of each leaf blade has conspicuous parallel veins. The leaf sheaths are the same color as the blades and they are hairless.
The culm terminates in a panicle of
spikelets up to 1½' long and half as much across. This panicle is
densely branched and its branchlets are ascending or drooping. While the
florets are in bloom, the panicle has a silky reddish appearance, although it
becomes light tan later in the year. Each spikelet is up to 2/3" long and it
has 3-7 florets; the lowest floret is sterile or staminate, while the remaining
florets are perfect. At the bottom of this spikelet, there is a pair of
linear-lanceolate glumes about ¼" long. The lemmas above the glumes are
linear in shape and up to ½" long, becoming smaller as they ascend the
rachilla (central stalk of the floret). Along the rachilla, there are tufts of
long silky hairs. The blooming period occurs during mid- to late summer. The
florets are wind-pollinated. Upon maturity, each perfect floret develops a
grain, but it is often abortive or sterile. The root system consists of stout
rhizomes and coarse fibrous roots. This grass often forms vegetative colonies
that are sometimes quite large in size.
Cultivation: The preference is full sun, wet
conditions (including shallow water), and a rich fertile soil to sustain the
prodigious growth of this grass. A little shade and soil that is merely moist
are tolerated. This grass can spread aggressively through its rhizomes.
Range & Habitat: Giant Reed occurs occasionally
in central and northern Illinois, while in the southern part of the state it is
uncommon. This species is native to Illinois and other parts of North America;
it also occurs in Eurasia, Africa, and Australia. Habitats include edges of
floodplain forests, swamps, wet prairies, marshes, edges and shallow water of
ponds and rivers, large drainage ditches, edges of poorly drained fields, and
wet areas along beaches. In some of these habitats, Giant Reed can become the
dominant wetland plant.
Faunal
Associations: The caterpillars of Poanes viator (Broad-Winged
Skipper) feed on the Giant Reed and other wetland grasses. This skipper can be
found in wetland areas of northern Illinois. Birds and mammals don't use Giant
Reed as a food plant to any significant degree. However, the tall coarse
foliage does provide cover for many species of wetland birds and other
animals.
Photographic Location: A
drainage ditch along a railroad in Champaign, Illinois.
Comments: Giant Reed is a very imposing species that
dwarfs most other grasses. In spite of its common name, the Giant Reed is a
grass (a member of the Grass family), rather than a reed (whatever that means).
With the exception of Arundinaria gigantea (Giant Cane), a species that
occurs only in southern Illinois, Giant Reed is the tallest native grass
species in Illinois. The Giant Cane is a native bamboo species that flowers
only once in about 50 years, while mature specimens of Giant Reed bloom every
year. Another grass species that can become as tall is Arundo donax,
which is also called 'Giant Reed.' This latter species is cultivated as an
ornamental grass and it is native to the Mediterranean area. The species
Arundo donax is tall and columnar; it has leaves that are shorter and
more spreading than those of Giant Reed. In Illinois, Arundo donax is
usually shorter than the Giant Reed, but in warmer climates it can become
taller. There is a less robust form of Arundo donax with variegated
leaves. So far, this introduced species has naturalized only rarely in southern
Illinois. A scientific synonym of Giant Reed is Phragmites communis,
while 'Common Reed' is another common name that is occasionally applied to this
native species.