This perennial sedge is 1-3' tall and erect. The culm is light green,
hairless, terete, relatively stout, hollow, and almost always
unbranched; it appears jointed because of the narrow brownish membranes
of the ligules. The lowest leaves have sheaths, but they lack blades,
causing the bottom of the culm to appear naked. The remaining leaves
have stiffly spreading to ascending blades that are strictly organized
into 3 equidistant ranks. These blades are 2-6" (5-15 cm.) long, 3-8
medium green, linear-lanceolate in shape, and shallowly furrowed; they
appear toothless along their margins. The tips of the blades are acute,
while their bases strongly clasp the culm. The sheaths surrounding the
culm are relatively tight, rather than loose. Axillary floral spikes
develop along the upper one-half of the culm. Immediately below the
spikes, there are leafy bracts with an appearance that is similar to
the leaves, but they are somewhat smaller in size overall; the leafy
also arranged into 3 ranks. Each floral spike is ¾–2" (2-5 cm.)
long, consisting of a slightly zigzag central axis with 7-20 linear
the latter are organized into 2 or 3 ranks. The spikelets are light
green during the blooming period, but they turn brown at maturity.
Peduncles (basal stalks) of the floral spikes vary from nearly zero to
1" (2.5 cm.) in length.
spikelet is ¾–1¼" (2-3 cm.) long,
consisting of 4-9 perfect florets and their scales. Each floret has 3
stamens and an ovary with a single white style; the style divides
into 2 narrow white stigmas at its tip. The anthers of the stamens
droop down conspicuously from slender filaments. Depending on their
maturity, the anthers are pale yellow to brown; they are 2-3 mm. long
and linear in shape. The scales of the spikelets are 5-8 mm. long, narrowly
oblong-lanceolate in shape, and tightly appressed; they have
membranous-brown margins. The blooming period occurs during mid-summer
to late summer, lasting about 2-3 weeks for a colony of plants; the
florets are cross-pollinated by the wind. During late summer to early
autumn, the spikelets become mature, and their scales with achenes
begin to disarticulate individually. Mature achenes are 2.5–3.5 mm.
long (excluding their persistent styles), narrowly oblongoid-ellipsoid in shape,
somewhat flattened, and light tan to light brown. The persistent styles of the
achenes are about the same length as the achenes. Each achene also has
6-9 barbed bristles that originate from its base, surrounding it
on all sides; these bristles are 1-2 times the length of the achene.
The root system is fibrous and slender-rhizomatous. Clonal colonies of
plants often develop from the rhizomes.
preference is full or partial sun, wet ground or shallow water (up to
6" deep), and a substrate containing abundant organic matter. This
sedge also grows on sandy muck. It prefers a cool moist climate,
although there are southern ecotypes of this sedge that tolerate more
heat if they receive some shade.
Habitat: The native
Three-way Sedge (Dulichium
arundinaceum) is uncommon in NE Illinois,
while in the rest of the state it is rare or absent (see Distribution
Map). It is found primarily in the Great Lakes region,
USA, and adjacent areas of Canada, however it also occurs more
sporadically in southeastern USA and the Pacific Northwest. At one
time, during earlier interglacial periods, this distinctive sedge also
occurred in Great Britain, France, and other areas of Europe, but it
has since become extinct there (Bell, 1970; Andrieu et al., 1997). Habitats
consist of various wetlands, including swamps and bottomland woodlands
(southern Illinois), shallow marshes, fens, bogs, mucky sand flats,
edges of streams, sinkhole ponds, sloughs, and edges of small lakes.
This sedge is found in high quality wetlands.
Associations: Information about floral-faunal
relationships for this
sedge is rather limited. The larvae of Ametrodiplosis dulichii
(Three-way Sedge Fruit Midge) feed on the spikelets and
seeds (Felt, 1917). The seeds are also a minor source of food for the
Blue-winged Teal and probably other dabbling ducks, while the lower
stems are eaten to a limited extent by muskrats (Mabbott, 1920;
Hamerstrom & Blake, 1939). Colonies of this rather tall leafy
provide protective cover for various kinds of wetland wildlife.
A marsh near Volo Bog in Lake County, Illinois.
Because of its erect habit, terete stems with a jointed appearance, and
strictly 3-ranked leaves, this unusual sedge is rather easy to
identify, even when its floral spikes are absent. Three-way sedge
is sometimes cultivated in wetland gardens,
and there is a cultivar with white-margined leaf blades. The spikes of
Three-way Sedge are similar in appearance to those of many Flatsedges
but its achenes have bristles and persistent styles.
In contrast, the achenes of Flatsedges lack bristles and persistent
Three-way Sedge produces axillary floral spikes (usually solitary
spikes, rarely compound spikes), while Flatsedges produce floral spikes
in a terminal inflorescence that consists of either a simple or
compound umbel. Another common name of Dulichium arundinaceum is Dwarf Water Bamboo.