Aristida oligantha Michx.

oldfield threeawn

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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

Oldfield threeawn is an annual, weedy grass that is a pioneer of secondary successional habitats and can dominate such habitats for many years. It can colonize pastures in the midwest after heavy grazing, and is considered an agricultural weed and poor forage. This species is introduced throughout New England, but is absent from most of Maine.

Habitat

Anthropogenic (man-made or disturbed habitats), grassland, meadows and fields

Characteristics

Habitat
terrestrial
New England state
  • Connecticut
  • Maine
  • Massachusetts
  • New Hampshire
  • Rhode Island
  • Vermont
Leaf blade width
0.5–1.5 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
18–25 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
8–70 mm
Leaf sheath hair type
there are hairs on the surface of the leaf sheath, but the hairs do not have blisters at their bases
Leaf ligule length
Up to 0.5 mm
Anther length
Up to 0.5 mm
Show All Characteristics
  • Flowers
    Anther length
    Up to 0.5 mm
    Anther number
    1
    Awn on glume
    • the glume has an awn
    • the glume has no awn
    Bristles below spikelets
    no
    Floret lower bract texture
    the lemma is hard and firm
    Floret number
    1
    Floret types within spikelet
    all the florets within a spikelet are similar
    Glume awn length
    1–13 mm
    Glume relative length
    both glumes are as long or longer than all of the florets
    Glume veins
    • 1
    • 3
    • 5
    • 7 or more
    Glumes per spikelet
    2
    Inflorescence arrangement
    the spikelets are uniform
    Inflorescence axis orientation
    the inflorescence axis is straight
    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 branches coming off the lowest stem node
    At least 0
    Inflorescence crowding
    the panicle is somewhat to very congested (crowded), and the branches may not be clearly seen without close inspection
    Inflorescence length
    50–200 mm
    Inflorescence length to width ratio
    2.5–5
    Inflorescence type (general)
    the inflorescence is a spike, or is spike-like, lacking obvious branches
    Inflorescence type (specific)
    • the inflorescence is a raceme (a long unbranched stem with stalked flowers growing along it)
    • the inflorescence is a spike (a long unbranched stem with flowers along it that lack stalks)
    Inflorescence width
    20–40 mm
    Inforescence position
    the spikelets are mainly carried at the end of the stem
    Lemma awn base
    the awn is attached right at the tip of the lemma
    Lemma awn coiled
    the lemma awn is straight or twisted, but not coiled one half turn
    Lemma awn length
    8–70 mm
    Lemma awn number
    the lemma has more than one awn on it
    Lemma base hairs
    the lemma has hairs at the base
    Lemma base length
    0.5–2 mm
    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 marginal vein hairs
    the marginal vein 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 vein number
    3
    Lower glume length
    12–70 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 relative length
    palea is one half to fully as long as lemma
    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
    18–25 mm
    Spikelet number per node
    0
    Spikelet pedicel
    the spikelets have pedicels
    Spikelets spiny
    the spikelets do not appear spiny
    Tip of glume
    • the tip of the glume is divided into two or more points
    • the tip of the glume is not divided (though it may have an awn on it)
    Upper glume length
    12–70 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
    8–14 mm
  • Growth form
    Horizontal rooting stem
    no
    Lifespan
    the plant lives only a single year or less
    Rhizomes
    no
    Roots
    there are only slender roots on the plant
  • 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 more or less flat in cross-section, or slightly 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
    4–12 cm
    Leaf blade width
    0.5–1.5 mm
    Leaf ligule length
    Up to 0.5 mm
    Leaf ligule type
    the leaf ligule is in the form of fine hairs
    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 hairs on the surface of the leaf sheath, but the hairs do not have blisters at their bases
    Leaf sheath hairs
    there are hairs on the surface of the leaf sheath
  • Place
    Habitat
    terrestrial
    New England state
    • Connecticut
    • Maine
    • Massachusetts
    • New Hampshire
    • Rhode Island
    • Vermont
    Specific habitat
    • grasslands
    • man-made or disturbed habitats
    • meadows or fields
  • Stem, shoot, branch
    Plant height
    25–55 cm
    Stem spacing
    the stems grow close together in compact clusters or tufts

Wetland Status

Not classified

New England Distribution and Conservation Status

Distribution

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

Conservation Status

Exact status definitions can vary from state to state. For details, please check with your state.

Massachusetts
not applicable (S-rank: SNA)

Native to North America?

Yes and no (some introduced)

Sometimes Confused With

Aristida tuberculosa:
lemma awns twisted together at the base forming a spiral column 8–15 mm tall and callus of lemma 3–4 mm long (vs. A. oligantha, with lemma awns not twisted together at the base and callus of lemma 0.5-2 mm long).

Family

Poaceae

Genus

Aristida

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Information from Dichotomous Key of Flora Novae Angliae

4.  Aristida oligantha Michx. E

oldfield threeawn. CT, MA, ME, NH, RI, VT; absent from most of ME. Sandy, often sterile, soils of fields, grasslands, roadsides, and disturbed areas. Though considered native by some authors, this grass is likely non-native in New England.