Agrostis exarata Trin.

spike bentgrass

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New England Distribution

Adapted from BONAP data

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North America Distribution

Adapted from BONAP data

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Facts About

The native range of spike bentgrass is western North America, where it occupies a wide range of habitats and altitudes. It is known in New England only from Vermont, where it is introduced.

Habitat

Anthropogenic (man-made or disturbed habitats), forest edges, forests

Characteristics

Habitat
terrestrial
New England state
Vermont
Leaf blade width
2–7 mm
Inflorescence branches
  • the flowers are attached to branches rather than to the main axis of the inflorescence
  • there are no branch points between the base of the inflorescence axis and the flowers, or they are not obvious
Spikelet length
1.5–3.5 mm
Glume relative length
both glumes are as long or longer than all of the florets
Awn on glume
  • the glume has an awn
  • the glume has no awn
One or more florets
there is one floret per spikelet
Lemma awn length
0–3.5 mm
Leaf sheath hair type
there are no hairs on the surface of the leaf sheath
Leaf ligule length
1–11.2 mm
Anther length
0.3–0.6 mm
Show All Characteristics
  • Flowers
    Anther length
    0.3–0.6 mm
    Anther number
    3
    Awn on glume
    • the glume has an awn
    • the glume has no awn
    Bristles below spikelets
    no
    Floret lower bract texture
    the lemma is thin and flexible
    Floret number
    1
    Floret types within spikelet
    all the florets within a spikelet are similar
    Glume awn length
    Up to 1 mm
    Glume keel
    the glume keels are rough or hairy
    Glume relative length
    both glumes are as long or longer than all of the florets
    Glume veins
    • 1
    • 3
    Glumes per spikelet
    2
    Inflorescence arrangement
    the spikelets are uniform
    Inflorescence axis orientation
    the inflorescence axis is straight
    Inflorescence branch length
    1–4 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
    • there are no branch points between the base of the inflorescence axis and the flowers, or they are not obvious
    Inflorescence crowding
    the panicle is somewhat to very congested (crowded), and the branches may not be clearly seen without close inspection
    Inflorescence length
    30–300 mm
    Inflorescence length to width ratio
    6–7.5
    Inflorescence type (general)
    • the inflorescence is a spike, or is spike-like, lacking obvious branches
    • 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
    5–40 mm
    Inforescence position
    the spikelets are mainly carried at the end of the stem
    Lemma awn base
    the awn is attached at the upper half of the lemma
    Lemma awn coiled
    the lemma awn is straight or twisted, but not coiled one half turn
    Lemma awn length
    0–3.5 mm
    Lemma awn number
    • the lemma has no awn
    • the lemma has one awn on it
    Lemma awn orientation
    • the awn of the lemma is straight
    • the awn of the lemma on dried or older plants is curved or bent outwards
    Lemma base hair length
    Up to 0.3 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 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)
    • the lemma tip is split into two or more points
    Lemma tip shape
    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
    1.5–3.5 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
    0–0.5 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
    1.5–3.5 mm
    Spikelet number per node
    0
    Spikelet position
    the spikelets emerge from both the upper and lower halves of the inflorescence branches
    Spikelet shape
    • the spikelets are lanceolate (lance-shaped, widest below the middle and tapering narrowly to the ends) in profile
    • 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
    1.5–3.5 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
    0.9–1.2 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 hairs
    the leaf blade is hairless, but it may have tiny prickles that give it a sand-papery feel
    Leaf blade length
    4–15 cm
    Leaf blade width
    2–7 mm
    Leaf ligule length
    1–11.2 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
    Vermont
    Specific habitat
    • edges of forests
    • forests
    • man-made or disturbed habitats
  • Stem, shoot, branch
    Plant height
    8–100 cm
    Roots at lower stem nodes
    • no
    • yes
    Stem node number
    2–8
    Stem orientation
    • the stems are upright
    • the stems trail at the base, but turn upwards at the tips
    Stem spacing
    • the stems grow close together in compact clusters or tufts
    • the stems grow singly or a few together (they may form diffuse colonies)

Wetland Status

Occurs in wetlands or non-wetlands. (Wetland indicator code: FAC)

New England Distribution and Conservation Status

Distribution

Connecticut
absent
Maine
absent
Massachusetts
absent
New Hampshire
absent
Rhode Island
absent
Vermont
present

Conservation Status

None

Native to North America?

Yes and no (some introduced)

Sometimes Confused With

Agrostis stolonifera:
paleas 0.7-1.4 mm long, anthers 0.9-1.4 mm long, and plants with stolons (vs. A. exarata, with paleas absent or up to 0.5 mm, anthers 0.3-0.6 mm long, and plants lacking stolons).

Synonyms

  • Agrostis exarata Trin. var. monolepis (Torrey) A.S. Hitchc.

Family

Poaceae

Genus

Agrostis

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Information from Dichotomous Key of Flora Novae Angliae

4.  Agrostis exarata Trin. E

spike bentgrass. Agrostis exarata Trin. var. monolepis (Torrey) A.S. Hitchc. • VT. Forest clearings, edges of gravel roads.