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- Poaceae
- Poaceae Group 7
- Agrostis
- Agrostis hyemalis
Agrostis hyemalis — winter bentgrass
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Facts
Winter bentgrass is a native perennial of eastern North America, that in New England is found mainly on the coastal plain. It is uncommon in our region, and another species, rough bentgrass (Agrostis scabra) is commonly mistaken for it. Winter bentgrass flowers much earlier than rough bentgrass (March through July vs. June through November), and has shorter lemmas (0.8 - 1.2 mm vs. 1.4 - 2mm), among other distinguishing characters.
Habitat
Anthropogenic (man-made or disturbed habitats), meadows and fields, woodlands
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
- terrestrial
- New England state
-
- Connecticut
- Maine
- Massachusetts
- New Hampshire
- Rhode Island
- Leaf blade width
- 1–2 mm
- Inflorescence branches
- the flowers are attached to branches rather than to the main axis of the inflorescence
- Spikelet length
- 1–2 mm
- Glume relative length
- one or both glumes are as long or longer than all of the florets
- Awn on glume
- the glume has no awn
- One or more florets
- there is one floret per spikelet
- Lemma awn length
- 0 mm
- Leaf sheath hair type
- there are no hairs on the surface of the leaf sheath
- Leaf ligule length
- 0.7–4 mm
- Anther length
- 0.2–0.5 mm
-
Flowers
- Anther length
- 0.2–0.5 mm
- Anther number
- 3
- Awn on glume
- the glume has no awn
- Bristles below spikelets
- no
- Floret lower bract texture
- the lemma is thin and flexible
- Floret number
- At least 1
- Floret types within spikelet
- all the florets within a spikelet are similar
- Glume awn length
- 0 mm
- Glume keel
- the glume keels are rough or hairy
- Glume relative length
- one or both glumes are as long or longer than all of the florets
- Glume shape
- the glume is V-shaped in cross-section
- Glume veins
- 1
- Glumes per spikelet
- 2
- Inflorescence arrangement
- the spikelets are uniform
- Inflorescence axis orientation
- the inflorescence axis is straight
- Inflorescence branch length
- 5–15 cm
- Inflorescence branch roughness
- the inflorescence branches are somewhat to very rough
- Inflorescence branches
- the flowers are attached to branches rather than to the main axis of the inflorescence
- Inflorescence branches coming off the lowest stem node
- 3–11
- Inflorescence crowding
- the panicle is somewhat to very spread out, with clearly-evident branches
- Inflorescence length
- 50–360 mm
- Inflorescence length to width ratio
- 1.5–1.7
- Inflorescence type (general)
- the spikelets are borne on stalks or on branches
- Inflorescence type (specific)
- the inflorescence is branched, and the branches do NOT both grow from the same side of the plant AND look like spikes
- Inflorescence width
- 30–240 mm
- Inforescence position
- the spikelets are mainly carried at the end of the stem
- Lemma awn base
- NA
- Lemma awn coiled
- NA
- Lemma awn length
- 0 mm
- Lemma awn number
- the lemma has no awn
- Lemma awn orientation
- NA
- Lemma base hair length
- Up to 0.2 mm
- Lemma base hairs
- the lemma has hairs at the base
- Lemma cross-section
- the lemma is flat or rounded if you cut across the midpoint
- Lemma hairs
- the lemma is hairless between the veins
- Lemma keel hairs
- the keel of the lemma is hairless
- Lemma surface
- the surface of the lemma is relatively smooth (not counting any longitudinal veins or hairs)
- Lemma tip
- the lemma tip is a simple point, with or without an awn (long narrow extension ending in a point)
- Lemma tip shape
-
- the lemma tip tapers to a broad point (it may or may not also have an awn or teeth at the tip)
- the lemma tip tapers to a narrow point (it may or may not also have an awn or teeth at the tip)
- Lemma vein number
- 5
- Lemma vein orientation
- the veins on the lemma stay roughly parallel throughout
- Lower glume length
- 1–2 mm
- Lower glume relative length
- the lower glume is nearly as long, or as long as, the upper glume
- One or more florets
- there is one floret per spikelet
- Palea length
- 0–0.2 mm
- Palea relative length
- palea is less than one half as long as lemma or absent
- Reproductive system
- all the flowers on the plant have both carpels and stamens (synoecious)
- Spikelet axis tip
- there is no extension of the spikelet axis beyond the tip of the spikelet
- Spikelet disintegration
- the spikelet breaks off above the glumes, so that after the florets fall off, the glumes remain
- Spikelet length
- 1–2 mm
- Spikelet number per node
- 0
- Spikelet pedicel
- the spikelets have pedicels
- Spikelet pedicel length
- 0.3–2 mm
- Spikelet position
- the spikelets emerge mainly from the upper halves of the inflorescence branches
- Spikelet shape
- the spikelets are ovate (egg-shaped, widest below the middle with rounded ends) in profile
- Spikelets spiny
- the spikelets do not appear spiny
- Tip of glume
- the tip of the glume is not divided (though it may have an awn on it)
- Upper glume length
- 1–2 mm
- Upper glume relative length
- the upper glume is more than one half as long as the lowest lemma
- Upper glume shape
- the upper glume is widest at or below the middle
-
Fruits or seeds
- Seed length
- 0.7–1 mm
-
Growth form
- Horizontal rooting stem
- no
- Lifespan
- the plant lives more than two years
- Rhizomes
- no
-
Leaves
- Basal leaves
- the plant has few or no leaves coming from the base of the flowering stem
- Leaf auricles
- the leaves do not have auricles
- Leaf basal lobe hairy
- NA
- Leaf blade cross-section
- the leaf blade is clearly folded or rolled inwards
- Leaf blade hairs
- the leaf blade is hairless, but it may have tiny prickles that give it a sand-papery feel
- Leaf blade length
- 3–10 cm
- Leaf blade width
- 1–2 mm
- Leaf ligule length
- 0.7–4 mm
- Leaf ligule type
- the leaf ligule is in the form of a membrane
- Leaf margin glands
- there are no glands along the edges of the leaf blade
- Leaf sheath closed around stem
- the margins of the leaf sheath are overlapping and not fused together except in the basal half (or less)
- Leaf sheath hair type
- there are no hairs on the surface of the leaf sheath
- Leaf sheath hairs
- there are no hairs on the surface of the leaf sheath
-
Place
- Habitat
- terrestrial
- New England state
-
- Connecticut
- Maine
- Massachusetts
- New Hampshire
- Rhode Island
- Specific habitat
-
- man-made or disturbed habitats
- meadows or fields
- woodlands
-
Stem, shoot, branch
- Plant height
- 15–82 cm
- Roots at lower stem nodes
- no
- Stem node number
- 3–7
- Stem orientation
- the stems are upright
- Stem spacing
- the stems grow close together in compact clusters or tufts
Wetland status
Occurs in wetlands or non-wetlands. (Wetland indicator code: FAC)
In New England
Distribution
- Connecticut
- present
- Maine
- present
- Massachusetts
- present
- New Hampshire
- present
- Rhode Island
- present
- Vermont
- absent
Conservation status
Exact status definitions can vary from state to state. For details, please check with your state.
- Massachusetts
- fairly widespread (S-rank: S4)
- Vermont
- widespread (S-rank: S5)
From Flora Novae Angliae dichotomous key
6. Agrostis hyemalis (Walt.) B.S.P. N
winter bentgrass. Cornucopiae hyemalis Walt. • CT, MA, ME, NH, RI; mainly on the coastal plain. Fields, roadsides, open woodlands. This uncommon species is over-reported, and many collections thought to be this grass are actually Agrostis scabra (including all of those from VT; collections at NEBC!, VT!).
Native to North America?
Yes
Sometimes confused with
- Agrostis scabra:
- glumes 1.8-3.4 mm long and lemmas 1.4-2 mm long (vs. A. hyemalis, with glumes 1-2 mm long and lemmas 0.8-1.2 mm long).
Synonyms
- Cornucopiae hyemalis Walt.