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- Rhynchospora inundata
Rhynchospora inundata — narrow-fruited beaksedge
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Facts
Narrow-fruited beaksedge is a very rare species in New England, with a few populations in each of Massachusetts and Rhode Island. It inhabits pond shores on the coastal plain. Like other rare species of this habitat type, it flowers and spreads vegetatively while inundated, but the seeds germinate readily only when the soil is dry. Thus, the timing and magnitude of water level fluctuations are important factors in population health.
Habitat
Shores of rivers or lakes
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.
Characteristics
- Habitat
- wetlands
- New England state
-
- Massachusetts
- Rhode Island
- Stem shape in cross-section
- the stem is roughly triangular in cross-section
- Leaf blade width
- 3–10 mm
- Leaf blade cross-section
-
- the leaf blade is flat or rolled in at the edges
- the leaf blade is triangular in cross-section
- Inflorescence position
-
- the inflorescence emerges from an axil, or most of its parts do so
- 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
- 4–5 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
- the fruit is lenticular (lens-shaped) in cross-section
-
Flowers
- Anther length
- 3.5–4 mm
- Floral bristle color
- the bristles are pale brown to brown
- Floral bristle number
- 5-7
- 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
- 9–13 mm
- Floral scale shape
- the floral scales are lanceolate (widest below the middle, and tapering at both ends)
- Flower number per cluster
-
- 1
- 2-5
- Inflorescence bract angle
- the bracts are vertical or angled only slightly outwards
- 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 emerges from an axil, or most of its parts do so
- 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
-
- 2
- 3
- Stigma number
-
- 1
- 2
- Style division
- the style is undivided, or divided only near the tip
- floral bristle barbs
- the bristles have tiny barbs on them
- plantlets budding at flower bases
- no
-
Fruits or seeds
- Achene beak length
- 0 mm
- Achene surface texture
- the achene has tiny wrinkles that run cross-wise across the achene
- Achene tubercle relative width
- the tubercle is one half to two thirds as wide as the achene
- 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
- the fruit is lenticular (lens-shaped) in cross-section
- Fruit length
- 4–5 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) with a tubercle (a swelling or projection, usually of a different color or texture) on it
- Locules in capsule
- NA
- Seed length
- 0 mm
- Seed tail relative length
- 0 mm
- Seed tails
- NA
- Tubercle height
- 10–15 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
- the leaf blade is triangular in cross-section
- Leaf blade width
- 3–10 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 blades
- there are fully-developed leaves with leaf blades on the main stem
-
Place
- Habitat
- wetlands
- New England state
-
- Massachusetts
- Rhode Island
- Specific habitat
- shores of rivers or lakes
-
Stem, shoot, branch
- Plant height
- 50–100 cm
- Stem shape in cross-section
- the stem is roughly triangular 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
- absent
- Maine
- absent
- Massachusetts
- present
- New Hampshire
- absent
- Rhode Island
- present
- Vermont
- absent
Conservation status
Exact status definitions can vary from state to state. For details, please check with your state.
- Massachusetts
- rare (S-rank: S2), threatened (code: T)
- Rhode Island
- extremely rare (S-rank: S1), state endangered (code: SE)
From Flora Novae Angliae dichotomous key
5. Rhynchospora inundata (Oakes) Fern. NC
narrow-fruited beaksedge. Ceratoschoenus macrostachys (Torr. ex Gray) Gray var. inundatus Oakes; Rhynchospora macrostachya Torr. ex Gray var. inundata (Oakes) Fern. • MA, RI. Coastal plain pond shores.
Native to North America?
Yes
Sometimes confused with
- Rhynchospora macrostachya:
- stems cespitose, without rhizomes, achene body 5–6 mm long, and achene tubercle mostly 18–20 mm long (vs. R. inundata, with stems not cespitose, produced from slender rhizomes, achene body 4–5 mm long, and achene tubercle 10–15 mm long).
Synonyms
- Ceratoschoenus macrostachys (Torr. ex Gray) Gray var. inundatus Oakes
- Rhynchospora macrostachya Torr. ex Gray var. inundata (Oakes) Fern.