Dulichium arundinaceum — three-way sedge
![Plant form: Dulichium arundinaceum. ~ By Marilee Lovit. ~ Copyright © 2024 Marilee Lovit. ~ lovitm[at]gmail.com](https://newfs.s3.amazonaws.com/taxon-images-1000s1000/Cyperaceae/dulichium-arundinaceum-ha-mlovit-a.jpg)
![Plant form: Dulichium arundinaceum. ~ By Marilee Lovit. ~ Copyright © 2024 Marilee Lovit. ~ lovitm[at]gmail.com](https://newfs.s3.amazonaws.com/taxon-images-1000s1000/Cyperaceae/dulichium-arundinaceum-ha-mlovit-c.jpg)
![Stems and sheaths: Dulichium arundinaceum. ~ By Ben Kimball. ~ Copyright © 2024 Ben Kimball. ~ alpinefin[at]comcast.net](https://newfs.s3.amazonaws.com/taxon-images-1000s1000/Cyperaceae/dulichium-arundinaceum-ss-bkimball.jpg)
![Inflorescences: Dulichium arundinaceum. ~ By Marilee Lovit. ~ Copyright © 2024 Marilee Lovit. ~ lovitm[at]gmail.com](https://newfs.s3.amazonaws.com/taxon-images-1000s1000/Cyperaceae/dulichium-arundinaceum-in-mlovit-b.jpg)
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Facts
Three-way sedge is the only member of its genus in New England. It inhabits river and lake shores and open wetlands. It is easily recognizable by its three ranked leaves. The three lines of leaves can be seen by looking down the stem from the top.
Habitat
Marshes, shores of rivers or lakes, wetland margins (edges of wetlands)
New England distribution
Adapted from BONAP data
Native: indigenous.
Non-native: introduced (intentionally or unintentionally); has become naturalized.
County documented: documented to exist in the county by evidence (herbarium specimen, photograph). Also covers those considered historical (not seen in 20 years).
State documented: documented to exist in the state, but not documented to a county within the state. Also covers those considered historical (not seen in 20 years).
Note: when native and non-native populations both exist in a county, only native status is shown on the map.
Found this plant? Take a photo and post a sighting.
enlargeCharacteristics
- Habitat
-
- aquatic
- terrestrial
- wetlands
- New England state
-
- Connecticut
- Maine
- Massachusetts
- New Hampshire
- Rhode Island
- Vermont
- Stem shape in cross-section
- the stem is round or oval in cross-section
- Leaf blade width
- 3.5–8 mm
- Leaf blade cross-section
- the leaf blade is flat or rolled in at the edges
- Inflorescence position
- the inflorescence emerges from an axil, or most of its parts do so
- Inflorescence branching
- the inflorescence is on one or more stems with no branches
- Fruit type (general)
- the fruit is like a seed, and surrounded by scales
- Fruit length
- 2–4 mm
- Leaf position on plant
- some leaf attachment points are above the midpoint of the stem
- Perianth composition
- there are bristles attached at the base of the achene
- Fruit cross-section
- the fruit is biconvex or elliptic (widest in the middle and tapering to both ends) in cross-section
-
Flowers
- Anther length
- 3–4 mm
- Floral bristle color
- the bristles are pale brown to brown
- Floral bristle number
-
- 5-7
- 8 or more
- Floral bristle relative length
- the bristles are longer than the achene
- Floral bristles
- the bristles are straight or slightly curved
- Floral scale hairs
- there are no hairs on the floral scales
- Floral scale length
- 5–9.5 mm
- Floral scale nerves
- 7 or more
- Floral scale shape
- the floral scales are lanceolate (widest below the middle, and tapering at both ends)
- Floral scale translucent
- the floral scales are opaque
- Flower number per cluster
-
- 2-5
- 5-20
- Inflorescence bract angle
- the bracts are vertical or angled only slightly outwards
- Inflorescence bract number
-
- there are six or more bracts per inflorescence
- there are two to five bracts per inflorescence
- Inflorescence bract position (Sparganium)
- NA
- Inflorescence bracts
- there are at least two bracts, and they are either flat or folded or rolled in at the edges
- Inflorescence branching
- the inflorescence is on one or more stems with no branches
- Inflorescence crowding
- the inflorescence is at least somewhat spread out, with at least one branch coming from the main stem
- Inflorescence position
- the inflorescence emerges from an axil, or most of its parts do so
- Inflorescence shape
- the aggregations within the inflorescence are at least somewhat flattened in cross-section
- Inflorescence type
- there are two or more flowers, spikes or flower clusters on a branched inflorescence
- Perianth composition
- there are bristles attached at the base of the achene
- Stamen number
- 3
- Stigma number
- 2
- Style division
- the top two thirds of the style is divided
- floral bristle barbs
- the bristles have tiny barbs on them
- plantlets budding at flower bases
- no
-
Fruits or seeds
- Achene tubercle relative width
- NA
- Achene tubercle width
- 0 mm
- Capsule relative length
- NA
- Fruit cross-section
- the fruit is biconvex or elliptic (widest in the middle and tapering to both ends) in cross-section
- Fruit length
- 2–4 mm
- Fruit type (general)
- the fruit is like a seed, and surrounded by scales
- Fruit type (specific)
- the fruit is an achene (dry, seed-like fruit) without a tubercle (a swelling or projection, usually of a different color or texture)
- Locules in capsule
- NA
- Seed length
- 0 mm
- Seed tail relative length
- 0 mm
- Seed tails
- NA
- Tubercle height
- 0 mm
-
Growth form
- Lifespan
- the plant lives more than two years
- Rhizome thickness
- 2–5 mm
- Underground organs
- the plant has a rhizome (a horizontal underground stem with roots growing from it)
-
Leaves
- Auricle length
- 0 mm
- Auricle texture
- NA
- Auricles
- there are no auricles on the leaf sheath
- Leaf blade cross-section
- the leaf blade is flat or rolled in at the edges
- Leaf blade length
- 40–150 mm
- Leaf blade width
- 3.5–8 mm
- Leaf form
- all the leaves hold their form out of water
- Leaf position on plant
- some leaf attachment points are above the midpoint of the stem
- Leaf septa
- the leaf blades do not have transverse septa
- Leaf sheath hairs
- the leaf sheathes are without hairs
- Pedicel length (Typha)
- 0 mm
- Stem leaf blade ligules
- the plant has ligules at the leaf blade bases
- Stem leaf blades
- there are fully-developed leaves with leaf blades on the main stem
-
Place
- Habitat
-
- aquatic
- terrestrial
- wetlands
- New England state
-
- Connecticut
- Maine
- Massachusetts
- New Hampshire
- Rhode Island
- Vermont
- Specific habitat
-
- edges of wetlands
- marshes
- shores of rivers or lakes
-
Stem, shoot, branch
- Plant height
- 20–100 cm
- Stem shape in cross-section
- the stem is round or oval in cross-section
- Stem texture near tip
- the stem feels smooth near the tip
- Stem thickness at midpoint
- 2–5 mm
Wetland status
Occurs only in wetlands. (Wetland indicator code: OBL)
In New England
Distribution
- Connecticut
- present
- Maine
- present
- Massachusetts
- present
- New Hampshire
- present
- Rhode Island
- present
- Vermont
- present
Conservation status
Exact status definitions can vary from state to state. For details, please check with your state.
- Massachusetts
- unranked (S-rank: SNR)
Subspecies and varieties
Our variety is Dulichium arundinaceum (L.) Britt. var. arundinaceum.
From Flora Novae Angliae dichotomous key
1. Dulichium arundinaceum (L.) Britt. var. arundinaceum N
three-way sedge. Cyperus arundinaceus L. • CT, MA, ME, NH, RI, VT. River shores, lake shores, marshes, and other open wetlands.
1×Rhynchospora capitellata. This very rare intergeneric hybrid is known from only MA within New England. It has been known by the name Cyperus ×weatherbianus Fern.; however, this name is incorrect as the plant is not part of the genus Cyperus (see Raymond (1962) for discussion). Further, the name should not have been a genus but rather a nothogenus (formed by combining in a specific manner the generic names of the species involved). The plant is identified by its general resemblance to R. capitellata with elongate, many-flowered (20–40 flowers) spikelets that resemble a species of Cyperus (except that the scales are spirally arranged and are terminated by a short awn). Most flowers are sterile and do not produce mature achenes, but those achenes that develop somewhat show a subulate tubercle at the apex of the achene body. The plant is further characterized by cespitose habit and terminal and axillary glomerules of spikelets (as in Rhynchospora) combined with flowers that lack perianth (as in Dulichium).