Dulichium arundinaceum (Three-way Sedge)

Plant Info
Also known as: Dwarf Bamboo
Family:Cyperaceae (Sedge)
Life cycle:perennial
Habitat:part shade, sun; wet; pond and lake shores, marshes, swamps, fens, bogs
Fruiting season:July - October
Plant height:10 to 40 inches
Wetland Indicator Status:GP: OBL MW: OBL NCNE: OBL
MN county distribution (click map to enlarge):Minnesota county distribution map
National distribution (click map to enlarge):National distribution map

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Detailed Information

spikes: Flower shape: indistinct Cluster type: spike

[photo of flowering spikes] 1 to 17 stalked spikes arising from leaf axils on the upper stem, each spike with 3 to 10 spikelets alternately arranged on the central stalk (rachis). Spikes are erect to ascending with spikelets ascending to spreading.

[photo of individual spike] Spikelets are 1.5 to 3 cm long (½ to 1 inch), very slender, somewhat flattened, with 4 to 8 perfect flowers (both male and female parts), each subtended by a scale. Scales are 5 to 9.5 mm long, 1.4 to 2.5 mm wide, lance-oblong, pointed at the tip, tightly appressed and overlapping, green with brown papery edging, and 5 to 9 nerves that are slightly rough.

Leaves and stems: Leaf attachment: alternate Leaf type: simple

[photo of 3-ranked leaves] Leaves are all alternate, spiraling the stem with 3 leaves in a cycle (3-ranked), appearing as 3 columns when viewed from the top. Leaves are hairless, flat, leathery, up to 6 inches long and 8 mm (1/3 inch) wide, becoming smaller on the upper stem and the lowest reduced to bladeless sheaths.

[photo of sheath] Sheaths are closed, surrounding the stem, convex to dome-shaped at the tip, papery with brown edging. The ligule (membrane where the leaf joins the sheath) has a band of loose, papery tissue along the edge. Stems are multiple from the base, erect, unbranched, round in cross-section, jointed, hairless, green, and usually leafy. Loose colonies are often formed from spreading rhizomes.

Fruit: Fruit type: seed without plume

[photo of spikelet, scale and achene] A flower produces a single seed (achene), the body 2 to 4 mm long, narrowly elliptic, flattened lens-shaped, the persistent style forming a slender beak about as long as the body. Surrounding the base are 5 to 9 slender, barbed bristles more or less equal in length and about as long as the achene including the beak.


Three-way Sedge is a common sedge of open, wet places including lake and pond shores, marshes and swamps, often growing in shallow water. More similar to Cyperus than Carex sedges, it is easy to identify from its unique 3-ranked leaves combined with round stems and spikes arising from the leaf axils. There are 2 recognized varieties of D. arundinacium: var. boreale is a smaller plant with a limited range in Canada, var. arundinaceum is described above and widespread in North America, especially east of the Mississippi River, and including Minnesota.

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More photos

Photos by K. Chayka taken at Cedar Creek Natural History Center, Anoka County. Photos courtesy Peter M. Dziuk taken in Aitkin, Anoka and Lake counties. Other photos courtesy Steve Eggers.


Have you seen this plant in Minnesota, or have any other comments about it?

Posted by: Brett W - Crow Wing County
on: 2022-07-31 14:09:33

Found along the lakeshore in the Milford Mine County Park in a couple of spots.

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