Aristida purpurea Nutt.

purple 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

Purple threeawn is a highly variable species with a number of varieties native to the western states. One variety has been introduced to New England (Aristida purpurea var. nealleyi), where it has been collected in disturbed sandy soil in Vermont.

Habitat

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

Characteristics

Habitat
terrestrial
New England state
Vermont
Leaf blade width
0.7–2 mm
Inflorescence branches
the flowers are attached to branches rather than to the main axis of the inflorescence
Spikelet length
11–15 mm
Glume relative length
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
15–30 mm
Leaf sheath hair type
there are no hairs on the surface of the leaf sheath
Leaf ligule length
0.3–0.6 mm
Anther length
0.7–2 mm
Show All Characteristics
  • Flowers
    Anther length
    0.7–2 mm
    Anther number
    3
    Awn on glume
    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 keel
    the glume keels are smooth and hairless
    Glume relative length
    both glumes are as long or longer than all of the florets
    Glume veins
    1
    Glumes per spikelet
    2
    Inflorescence arrangement
    the spikelets are uniform
    Inflorescence axis orientation
    the inflorescence axis is straight
    Inflorescence branch length
    3–6 cm
    Inflorescence branches
    the flowers are attached to branches rather than to the main axis of the inflorescence
    Inflorescence length
    80–200 mm
    Inflorescence length to width ratio
    1.7–4
    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
    20–120 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
    15–30 mm
    Lemma awn number
    the lemma has more than one awn on it
    Lemma base hairs
    the lemma is hairless or feels just a tiny bit rough 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 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
    4–7 mm
    Lower glume relative length
    the lower glume is one third to three quarters 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
    11–15 mm
    Spikelet number per node
    0
    Spikelet pedicel
    the spikelets have pedicels
    Spikelets spiny
    the spikelets do not appear spiny
    Upper glume length
    7–14 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
    6–14 mm
  • Growth form
    Horizontal rooting stem
    no
    Lifespan
    the plant lives more than two years
    Rhizomes
    no
  • Leaves
    Basal leaves
    the plant has large or prominent tufts of leaves at 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 length
    5–15 cm
    Leaf blade width
    0.7–2 mm
    Leaf ligule length
    0.3–0.6 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 color and persistence
    the leaf sheathes are off-white to light-brown and mostly persist in older leaves
    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
    • grasslands
    • man-made or disturbed habitats
    • meadows or fields
  • Stem, shoot, branch
    Plant height
    20–45 cm
    Stem orientation
    the stems are upright
    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
absent
Massachusetts
absent
New Hampshire
absent
Rhode Island
absent
Vermont
present

Conservation Status

None

Native to North America?

Yes

Sometimes Confused With

Aristida purpurascens:
lower glume 5-10 mm long and usually more than 75% as long as the upper glume, and lemmas 4-8 mm long, with a callus 0.4-0.8 mm long (vs. A. purpurea, with lower glume 4-7 mm long and usually less than 75% as long as the upper glume, and lemmas 7-13 mm long, with a callus 0.5-1.8 mm long).

Synonyms

  • Aristida glauca (Nees) Walp.
  • Aristida nealleyi (Vasey) Vasey

Family

Poaceae

Genus

Aristida

Notes on Subspecies and Varieties in New England

Our variety is Aristida purpurea Nutt. var. nealleyi (Vasey) Allred.

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Information from Dichotomous Key of Flora Novae Angliae

6.  Aristida purpurea Nutt. var. nealleyi (Vasey) Allred E

purple threeawn. Aristida glauca (Nees) Walp.; A. nealleyi (Vasey) Vasey • VT. Roadsides, disturbed, sandy soil.