Scirpus hattorianus — mosquito bulrush
![Inflorescences: Scirpus hattorianus. ~ By Arthur Haines. ~ Copyright © 2024 Arthur Haines. ~ arthur.d.haines[at]gmail.com](https://newfs.s3.amazonaws.com/taxon-images-1000s1000/Cyperaceae/scirpus-hattorianus-in-ahaines.jpg)
Copyright: various copyright holders. To reuse an image, please click it to see who you will need to contact.
Facts
Mosquito bulrush is native to North America but was first described from plants that were introduced into Japan. It is often mistaken for its close relative dark-green bulrush (Scirpus atrovirens).
Habitat
Anthropogenic (man-made or disturbed habitats), marshes, meadows and fields, 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
-
- terrestrial
- wetlands
- New England state
-
- Connecticut
- Maine
- Massachusetts
- New Hampshire
- Rhode Island
- Vermont
- Stem shape in cross-section
-
- the stem is roughly triangular in cross-section
- the stem is round or oval in cross-section
- Leaf blade width
- 5–9 mm
- Leaf blade cross-section
- the leaf blade is flat or rolled in at the edges
- Inflorescence position
- the inflorescence is at the tip of the plant
- Inflorescence branching
- the inflorescence is branched
- Fruit type (general)
- the fruit is like a seed, and surrounded by scales
- Fruit length
- 0.7–1.1 mm
- Leaf position on plant
-
- some leaf attachment points are above the midpoint of the stem
- the attachment points of all the leaves are at or near the base of the plant
- Perianth composition
- there are bristles attached at the base of the achene
- Fruit cross-section
- the fruit is triangular to terete (circular) in cross-section
-
Flowers
- Floral bristle color
- the bristles are pale brown to brown
- Floral bristle number
- 5-7
- Floral bristle relative length
- the bristles are between one tenth as long as the achene, and equal in length to 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
- 1–2 mm
- Floral scale nerves
- 1
- Floral scale shape
- the floral scales are elliptic (widest in the middle and tapering toward each end)
- Floral scale translucent
- the floral scales are opaque
- Inflorescence bract angle
- the bracts are angled outwards near horizontal or reflexed downwards
- Inflorescence bract number
- 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 branched
- Inflorescence crowding
- the inflorescence is crowded together in one tight cluster
- Inflorescence position
- the inflorescence is at the tip of the plant
- Inflorescence shape
- the aggregations within the inflorescence are roughly circular (not 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
-
- 1
- 2
- 3
- Stigma number
- 3
- Style division
- the top two thirds of the style is divided
- floral bristle barbs
- the bristles have tiny barbs on them
-
Fruits or seeds
- Achene tubercle relative width
- NA
- Achene tubercle width
- 0 mm
- Capsule relative length
- NA
- Fruit cross-section
- the fruit is triangular to terete (circular) in cross-section
- Fruit length
- 0.7–1.1 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
- 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
- 200–350 mm
- Leaf blade width
- 5–9 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
- the attachment points of all the leaves are at or near the base of the plant
- 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
-
- terrestrial
- wetlands
- New England state
-
- Connecticut
- Maine
- Massachusetts
- New Hampshire
- Rhode Island
- Vermont
- Specific habitat
-
- edges of wetlands
- man-made or disturbed habitats
- marshes
- meadows or fields
-
Stem, shoot, branch
- Plant height
- Up to 150 cm
- Stem shape in cross-section
-
- the stem is roughly triangular in cross-section
- the stem is round or oval in cross-section
- Stem texture near tip
- the stem feels smooth near the tip
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
- widespread (S-rank: S5)
From Flora Novae Angliae dichotomous key
7. Scirpus hattorianus Makino N
mosquito bulrush. CT, MA, ME, NH, RI, VT. Wet fields, graminoid marshes, ditches, open, seasonally wet areas.
2×7. Scirpus atrocinctus × Scirpus hattorianus → Scirpus ×peckii Britt. is an uncommon bulrush nothospecies that is known from CT, MA, ME, NH, RI, VT. It has individual spikelets that somewhat resemble those of S. atrocinctus; however, the clusters of spikelets are borne on relatively stiff, straight inflorescence branches. The perianth bristles are elongate and somewhat bent but have a few remote barbules along their length. This hybrid appears to be much less frequent in the southern New England states.
Native to North America?
Yes
Sometimes confused with
- Scirpus atrovirens:
- fruits 1.1-1.3 mm long with perianth bristles longer than the fruits (vs. S. hattorianus, with fruits 0.8-1.1 mm long, with perianth bristles that are shorter than to as long as the fruit).
- Scirpus georgianus:
- perianth bristles numbering 0–3 per flower, up to 0.7 times as long as the achene, smooth or with barbs only near the very apex (vs. S. hattorianus, with perianth bristles numbering mostly 5 or 6 per flower, more than 0.6 times as long as the achene, barbed in the apical half).