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Triplasis purpurea — purple sandgrass

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Facts

Purple sandgrass is native to the eastern and central United States, and is an annual grass of shifting dunes. In New England it inhabits the upper sections of sandy beaches along the Atlantic coast, as well as occasionally further inland on sandy soils. It has an unusual feature for a grass: in addition to its conventional wind-pollinated flowers, it possesses cleistogamous (closed, self-fertilizing) flowers on spikelets tucked within the leaf sheaths.

Habitat

Coastal beaches (sea beaches), dunes

New England distribution

Adapted from BONAP data

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North America distribution

Adapted from BONAP data

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Characteristics

Habitat
terrestrial
New England state
  • Connecticut
  • Maine
  • Massachusetts
  • New Hampshire
  • Rhode Island
Leaf blade width
1–5 mm
Inflorescence branches
the flowers are attached to branches rather than to the main axis of the inflorescence
Spikelet length
6.5–9 mm
Glume relative length
neither glume is quite as long as all of the florets
Awn on glume
the glume has no awn
One or more florets
there is more than one floret per spikelet
Lemma awn length
0–2 mm
Leaf sheath hair type
there are no hairs on the surface of the leaf sheath
Leaf ligule length
0.5–1 mm
Show all characteristics

  • Flowers

    Awn on glume
    the glume has no awn
    Glume relative length
    neither glume is quite as long as all of the florets
    Glume veins
    1
    Inflorescence arrangement
    the spikelets are uniform
    Inflorescence axis orientation
    • the inflorescence axis is arched or curved outward
    • the inflorescence axis is straight
    Inflorescence branches
    the flowers are attached to branches rather than to the main axis of the inflorescence
    Inflorescence length
    30–70 mm
    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
    Inforescence position
    • the spikelets are mainly carried at the end of the stem
    • the spikelets are mainly found at the nodes, in the axils of leaves, along the stem
    Lemma awn base
    the awn is attached right at the tip of the lemma
    Lemma awn length
    0–2 mm
    Lemma awn number
    • the lemma has no awn
    • the lemma has one awn on it
    Lemma cross-section
    the lemma is V-shaped 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 split into two or more points
    Lemma vein number
    3
    One or more florets
    there is more than one floret per spikelet
    Palea relative length
    palea is one half to fully as long as lemma
    Spikelet axis tip
    there is an extension of the spikelet axis beyond the tip of the spikelet
    Spikelet length
    6.5–9 mm
    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 shape
    the upper glume is widest at or below the middle

  • Leaves

    Leaf auricles
    the leaves do not have auricles
    Leaf blade width
    1–5 mm
    Leaf ligule length
    0.5–1 mm
    Leaf ligule type
    the leaf ligule is in the form of fine hairs
    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
    • dunes
    • sea beaches

  • Stem, shoot, branch

    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

Not classified

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.

var. purpurea

Massachusetts
fairly widespread (S-rank: S4)
New Hampshire
historical (S-rank: SH), endangered (code: E)

From Flora Novae Angliae dichotomous key

1.  Triplasis purpurea (Walt.) Chapman var. purpurea N

purple sandgrass. Triplasis intermedia Nash • CT, MA, ME, NH, RI. Upper sand beaches and dunes along the Atlantic coast, less frequently inland in sandy soils.

Native to North America?

Yes

Sometimes confused with

Sporobolus vaginiflorus:
lemmas unawned, lower glumes 2.2-4.7 mm long, leaf blades 0.8-2 mm wide, and stems not disarticulating at the nodes (vs. T. purpurea, lemmas shortly awned, lower glumes 2-2.5 mm long, leaf blades 1-5 mm wide, and stems disarticulating at the nodes).

Synonyms

  • Triplasis intermedia Nash

Family

Poaceae

Genus

Triplasis