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• Dichotomous Key
• Poaceae
• Poaceae Group 7
• Agrostis
• Agrostis exarata

Agrostis exarata — spike bentgrass

Facts

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

• 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

From the dichotomous key of Flora Novae Angliae