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• True grasses
• Phragmites americanus

Phragmites americanus — American reed

Facts

American reed is the native close relative to the invasive common reed (Phragmites australis). Until recently these two taxa were not distinguished, and efforts to eradicate the common reed may have impacted populations of the less common American reed. However, they are relatively easy to distinguish, and genetic studies confirm these morphological differences. The most apparent distinguishing field character is that the middle and upper stem internodes of American reed are smooth, shiny and red-brown to dark red-brown during the growing season. In common reed by contrast, the middle to upper stem internodes are dull, ridged, and tan-colored during the growing season.

Habitat

Brackish or salt marshes and flats, fens (calcium-rich wetlands), fresh tidal marshes or flats, shores of rivers or lakes

Characteristics

• Flowers

  Anther length

  1.5–2 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

  2–8

  Floret types within spikelet

  there are at least two distinct forms of florets within one spikelet

  Glume relative length

  neither glume is quite as long as 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 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 crowding

  • the panicle is somewhat to very congested (crowded), and the branches may not be clearly seen without close inspection
  • the panicle is somewhat to very spread out, with clearly-evident branches

  Inflorescence length

  150–350 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

  Lemma awn base

  NA

  Lemma awn coiled

  NA

  Lemma awn length

  0 mm

  Lemma awn number

  the lemma has no awn

  Lemma base hair length

  6–12 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 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

  3–6.5 mm

  One or more florets

  there is more than one floret per spikelet

  Reproductive system

  some flowers on the plant have both carpels and stamens, while other flowers have only one type of reproductive organ (polygamous)

  Spikelet axis tip

  there is no extension of the spikelet axis beyond the tip of the spikelet

  Spikelet length

  12–18 mm

  Spikelets spiny

  the spikelets do not appear spiny

  Upper glume length

  3–6.5 mm

  Upper glume shape

  the upper glume is widest at or below the middle

• Growth form

  Lifespan

  the plant lives more than two years

  Rhizomes

  yes

  Roots

  the plant has rhizomes (horizontal underground stem with roots growing from it)

• 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
  • the leaves have auricles

  Leaf blade cross-section

  the leaf blade is more or less flat in cross-section, or slightly folded or rolled inwards

  Leaf blade width

  20–40 mm

  Leaf ligule length

  1–1.7 mm

  Leaf ligule type

  the leaf ligule is in the form of a membrane with 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 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

  wetlands

  New England state

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

  Specific habitat

  • brackish or salt marshes and flats
  • fens (calcium-rich wetlands)
  • fresh tidal marshes or flats
  • shores of rivers or lakes

• Stem, shoot, branch

  Stem hairs

  the stem is nearly to completely hairless

  Stem orientation

  the stems are upright

  Stem spacing

  the stems grow singly or a few together (they may form diffuse colonies)

Wetland status

Not classified

New England distribution and conservation status

From the dichotomous key of Flora Novae Angliae