Schoenoplectus purshianus — weak-stalked annual-bulrush
![Inflorescences: Schoenoplectus purshianus. ~ By Elizabeth Farnsworth. ~ Copyright © 2024 New England Wild Flower Society. ~ Image Request, images[at]newenglandwild.org](https://newfs.s3.amazonaws.com/taxon-images-1000s1000/Cyperaceae/schoenoplectus-purshianus-in-efarnsworth.jpg)
![Leaves and auricles: Schoenoplectus purshianus. ~ By Troy University Herbarium. ~ Copyright © 2024. ~ Brian Keener, bkeener[at]uwa.edu ~ Troy U. Herbarium](https://newfs.s3.amazonaws.com/taxon-images-1000s1000/Cyperaceae/schoenoplectus-purshianus-la-troyherb1.jpg)
![Inflorescences: Schoenoplectus purshianus. ~ By Arthur Haines. ~ Copyright © 2024 Arthur Haines. ~ arthur.d.haines[at]gmail.com](https://newfs.s3.amazonaws.com/taxon-images-1000s1000/Cyperaceae/schoenoplectus-purshianus-purshianus-in-ahaines-b.jpg)
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Facts
Weak-stalked bulrush inhabits pond shores and temporary pools in all New England states. There are two varieties, one of which is common and widespread (Schoenoplectus purshianus var. purshianus), the other (S. purshianus var. williamsii) being known from only a single population in Massachusetts.
Habitat
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
- 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
- 0.5–1 mm
- Leaf blade cross-section
-
- NA
- the leaf blade is flat or rolled in at the edges
- Inflorescence position
-
- the inflorescence appears to come from the side of the plant because the involucral bract at its base looks like an extension of the main stem
- 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
- 1.75–2 mm
- Leaf position on plant
- 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
- there is no perianth on the plant
- Fruit cross-section
- the fruit is biconvex or elliptic (widest in the middle and tapering to both ends) in cross-section
-
Flowers
- Anther length
- 0.4–0.6 mm
- Floral bristle color
- the bristles are pale brown to brown
- Floral bristle number
-
- 0
- 5-7
- Floral bristle relative length
-
- the bristles are between one tenth as long as the achene, and equal in length to the achene
- the bristles are longer than the achene
- Floral bristles
- the bristles are straight or slightly curved
- Floral scale hairs
- the floral scales have hairs on them
- Floral scale length
- 2.5–3 mm
- Floral scale nerves
-
- 2-5
- 7 or more
- Floral scale shape
- the floral scales are obovate (roughly egg-shaped, but with the widest part above the middle)
- 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 is just one bract on the inflorescence
- Inflorescence bract position (Sparganium)
- NA
- Inflorescence bracts
- there is only one bract, and it looks like a continuation of the stem
- Inflorescence branching
- the inflorescence is branched
- Inflorescence crowding
-
- NA
- the inflorescence is crowded together in one tight cluster
- Inflorescence position
-
- the inflorescence appears to come from the side of the plant because the involucral bract at its base looks like an extension of the main stem
- 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
- there is one spike or raceme at the tip of the stem
- Perianth composition
-
- there are bristles attached at the base of the achene
- there is no perianth on the plant
- Stamen number
- 3
- Stigma number
-
- 2
- 3
- 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 beak length
- 0.1–0.3 mm
- Achene surface texture
- the achene has very obvious pits or depressions on it
- 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
- 1.75–2 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 only a single year or less
- Rhizome thickness
- 1 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
-
- NA
- the leaf blade is flat or rolled in at the edges
- Leaf blade width
- 0.5–1 mm
- Leaf form
- all the leaves hold their form out of water
- Leaf position on plant
- 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 no leaves on the main stem, or there is a small tooth or tiny blade, or a leaf sheath with no blade
-
Place
- Habitat
- wetlands
- New England state
-
- Connecticut
- Maine
- Massachusetts
- New Hampshire
- Rhode Island
- Vermont
- Specific habitat
-
- edges of wetlands
- shores of rivers or lakes
-
Stem, shoot, branch
- Plant height
- 10–100 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
- 0.5–1 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.
var. purshianus
- Massachusetts
- fairly widespread (S-rank: S4S5)
- Vermont
- uncommon (S-rank: S3)
var. williamsii
- Massachusetts
- historical (S-rank: SH), H (code: H)
Subspecies and varieties
Variety purshianus is known from CT, MA, ME, NH, RI, VT. Variety williamsii is known from only MA in New England (and then from only the type locality in Norfolk County). It is of regional conservation concern.
From Flora Novae Angliae dichotomous key
7. Schoenoplectus purshianus (Fern.) M.T. Strong NC
weak-stalked annual-bulrush. 7a. Scirpus debilis Pursh; S. purshianus Fern.; 7b. Scirpus juncoides Roxb. var. williamsii (Fern.) T. Koyama; S. purshianus Fern. var. williamsii Fern. • CT, MA, ME, NH, RI, VT. Sandy or peaty pond shores and temporary pools.
1a. Flowers with 6 perianth bristles that equal or exceed the length of the achene … 7a. S. purshianus var. purshianus
1b. Flowers without perianth bristles … 7b. S. purshianus var. williamsii (Fern.) S.G. Sm.
Variety purshianus is known from CT, MA, ME, NH, RI, VT. Variety williamsii is known from only MA in New England (and then from only the type locality in Norfolk County). It is of regional conservation concern.
Native to North America?
Yes
Sometimes confused with
- Schoenoplectus smithii:
- fruits obscurely pitted and tapering at the base and floral scales lacking a distinct midvein (vs. S. purshianus, with fruits pitted on the surface and rounded near the base and floral scales with a distinct midvein).
- Schoenoplectus hallii:
- leaf-bearing nodes basal and one on the stem and achenes with prominent, transverse, wavy ridges, almost always lacking perianth bristles (vs. S. purshianus, with leaf-bearing nodes confined to the very base of the stem and achenes pitted to nearly smooth, with or without perianth bristles).
Synonyms
- Scirpus debilis Pursh
- Scirpus purshianus Fern.