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- Carex oronensis
Carex oronensis — Orono sedge
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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.
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Facts
Orono sedge is Maine's only endemic plant, meaning it occurs nowhere else. There are a total of about 58 known populations occuring on road-sides, fields, meadows, power lines, river shores and clearings, mainly in the Penobscot River drainage. The biggest known population was lost to plowing in 1991.
Habitat
Anthropogenic (man-made or disturbed habitats), meadows and fields
Characteristics
- Habitat
- terrestrial
- New England state
- Maine
- stem leaf blade width
- 2–4 mm
- Lowest bract sheath
- the lowest bract has no sheath (or a very short sheath up to four millimeters in length)
- Spike on stalk
- the lowest spike on the plant is not borne on a peduncle
- Top spike
- the uppermost spike contains both staminate and carpellate flowers, with the staminate flowers located below the carpellate flowers
- Perigynium hairs
- the perigynium has no hairs
- Perigynium length
- 2.9–4.3 mm
- Leaf sheath color
- the leaf sheath has no pink, red or purple tinting
- Leaf blade texture
- the leaf blade is smooth and hairless, or rough and sandpapery
- Perigynium beak teeth
- the perigynium beak is divided at the top into two teeth
-
Flowers
- Bumps on fruit
- there are no papillae on the perigynium surface
- Inflorescence length
- 15–34 mm
- Length of scale
-
- the scale is nearly as long as, or longer than, the perigynium
- the scale is shorter than the perigynium
- Lowest spike length
- 5–10 mm
- Lowest spike stalk length
- 0 mm
- Lowest spike width
- 3–7 mm
- Perigynium beak
- the perigynium has a beak
- Perigynium beak orientation
- the beak of the perigynium is straight, and in line with the perigynium
- Perigynium beak serrations
- the perigynium beak has tiny serrations along the edges
- Perigynium beak teeth
- the perigynium beak is divided at the top into two teeth
- Perigynium color
-
- green
- tan
- Perigynium cross-section
- the perigynium is planoconvex (flat on one surface and rounded on the other) in cross-section
- Perigynium hairs
- the perigynium has no hairs
- Perigynium length
- 2.9–4.3 mm
- Perigynium nerve number
- 13–27
- Perigynium nerve texture
- the nerves on the perigynium are raised, even after drying the perigynium
- Perigynium nerves lower side
- 7–15
- Perigynium nerves upper side
- 6–12
- Perigynium orientation
- the perigynia are oriented vertically or pressed against the axis or adjacent perigynia
- Perigynium puffy
- the achene is tightly enclosed by the perigynium
- Perigynium shape
- the perigynium body is lanceolate (lance-shaped; widest below the middle and tapering at both ends)
- Perigynium width
- 0.9–1.4 mm
- Perigynium winged
- the perigynium has wings on it
- Pollen- and seed-producing spikes
- some of the spikes produce perigynia
- Pollen-producing spike length
- 0 mm
- Pollen-producing spike number
- 0
- Pollen-producing spike peduncle length
- 0 mm
- Pollen-producing spike width
- 0 mm
- Scale awn
- The carpellate scale does not have an awn (it may have a short point)
- Scale awn texture
- NA
- Scale color
- brown
- Scale length
- 3–4 mm
- Scale tip
- the carpellate scale tip is acute (has a sharp point)
- Spike on stalk
- the lowest spike on the plant is not borne on a peduncle
- Spike orientation
- the spikes are oriented vertically or pressed against the axis
- Spikes per stem
- 2-15
- Stigma branching
- the stigmas have two branches
- Top spike
- the uppermost spike contains both staminate and carpellate flowers, with the staminate flowers located below the carpellate flowers
-
Fruits or seeds
- Achene dimples
- the achene has no folds or dimples
- Achene length
- 1.3–1.6 mm
- Achene width
- 0.7–1.4 mm
- Style persistence
- the style falls off the mature achenes
-
Growth form
- Rhizomes
- there are no rhizomes, or the rhizomes are very short
-
Leaves
- Leaf arrangement
- the leaves are all produced from the base of the plant
- Leaf blade cross-section
- The leaf blade is folded lengthwise, with one prominent midvien
- Leaf blade length to width ratio
- 58–90
- Leaf blade texture
- the leaf blade is smooth and hairless, or rough and sandpapery
- Leaf bumps
- the upper surface of the leaf blade does not have papillae
- Leaf sheath bumps
- the top edge of the leaf sheath has papillae on it
- Leaf sheath color
- the leaf sheath has no pink, red or purple tinting
- Leaf sheath dots
- there are no dots on the leaf sheathes
- Leaf sheath folds
- there are no corrugations on the leaf sheath
- Leaf sheath texture
- the leaf sheath feels smooth, and has no hairs
- Ligule length
- 2.1–4.6 mm
- Lowest bract sheath
- the lowest bract has no sheath (or a very short sheath up to four millimeters in length)
- Lowest leaf blade width
- 2–4 mm
- Lowest leaf sheath texture
- the leaf sheath feels smooth (it may have soft hairs)
- stem leaf blade width
- 2–4 mm
-
Place
- Habitat
- terrestrial
- New England state
- Maine
- Specific habitat
-
- man-made or disturbed habitats
- meadows or fields
-
Stem, shoot, branch
- Plant height
- 30–100 cm
- Relative stem height
- the main stem is taller than the leaves
- Spike internode length
- 1–9 mm
- Stem cross-section
- the main stem is roughly triangular in cross-section
- Stem spacing
- the stems grow close together in compact clusters or tufts
Wetland status
Not classified
New England distribution and conservation status
Distribution
- Connecticut
- absent
- Maine
- present
- Massachusetts
- absent
- New Hampshire
- absent
- Rhode Island
- absent
- Vermont
- absent
Conservation status
Exact status definitions can vary from state to state. For details, please check with your state.
- Maine
- uncommon (S-rank: S3), threatened (code: T)
Native to North America?
Yes
Sometimes confused with
- Carex ovalis:
- perigynium 1.3-2.1 mm wide, with a beak that is cylindric, unwinged, and entire in the apical 0.3-0.5 mm (vs. C. oronensis, with a perigynium 0.9-1.4 mm wide, with a beak that is flat, winged, and serrulate to the apex).
Family
Genus
From the dichotomous key of Flora Novae Angliae
52. Carex oronensis Fern. NC
Orono sedge. ME; endemic to the state, mainly in the Penobscot River drainage. Wet-mesic to xeric open places such as fields, roadsides, and abandoned paths.