Glyceria grandis S. Wats.

American manna grass

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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

Many species of manna grass, including American manna grass, are planted ornamentally due to their attractive panicles. American manna grass has been known to cause cyanide poisoning in cattle. However, the grains are edible, as in other manna grasses (Glyceria).

Habitat

Anthropogenic (man-made or disturbed habitats), floodplain (river or stream floodplains), lacustrine (in lakes or ponds), marshes, meadows and fields, riverine (in rivers or streams), wetland margins (edges of wetlands)

Characteristics

Habitat
  • aquatic
  • wetlands
New England state
  • Connecticut
  • Maine
  • Massachusetts
  • New Hampshire
  • Vermont
Leaf blade width
4.5–15 mm
Inflorescence branches
the flowers are attached to branches rather than to the main axis of the inflorescence
Spikelet length
3.2–6.4 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 mm
Leaf sheath hair type
there are no hairs on the surface of the leaf sheath
Leaf ligule length
1–7 mm
Anther length
0.5–1.2 mm
Show All Characteristics
  • Flowers
    Anther length
    0.5–1.2 mm
    Anther number
    2–3
    Awn on glume
    the glume has no awn
    Bristles below spikelets
    no
    Floret lower bract texture
    the lemma is thin and flexible
    Floret number
    4–8
    Floret types within spikelet
    all the florets within a spikelet are similar
    Glume awn length
    0 mm
    Glume relative length
    neither glume is quite as long as all of the florets
    Glume veins
    1
    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 branch length
    7–18 cm
    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 spread out, with clearly-evident branches
    Inflorescence length
    160–420 mm
    Inflorescence length to width ratio
    1.3–2.1
    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
    120–200 mm
    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 awn orientation
    NA
    Lemma base hair length
    0 mm
    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 keel hairs
    the keel of the lemma is rough, or has fine hairs
    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 tip shape
    • the lemma tip is rounded off or truncate (ends abruptly in a more or less straight line as though cut off); it may or may not also have an awn or teeth at the tip
    • the lemma tip tapers to a broad point (it may or may not also have an awn or teeth at the tip)
    Lemma vein number
    • 5
    • 7 or more
    Lemma vein orientation
    the veins on the lemma stay roughly parallel throughout
    Lower glume length
    1–2.3 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 more than one floret per spikelet
    Palea relative length
    • palea is longer than lemma
    • 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
    3.2–6.4 mm
    Spikelet number per node
    0
    Spikelet pedicel
    the spikelets have pedicels
    Spikelet pedicel length
    1–15 mm
    Spikelet shape
    • the spikelets are elliptic (widest in the middle, tapering to the ends) in profile
    • the spikelets are ovate (egg-shaped, widest below the middle with rounded ends) in profile
    Spikelet width
    2–3 mm
    Spikelets per panicle branch
    35–80
    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
    1.5–2.7 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
    1–1.5 mm
  • Growth form
    Horizontal rooting stem
    no
    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
    Leaf basal lobe hairy
    NA
    Leaf blade base
    the leaf blade cuts in abruptly to the narrower base, or has rounded lobes on either side of the base (heart-shaped)
    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
    25–43 cm
    Leaf blade texture
    • the leaf blade is rough and sandpapery
    • the leaf blade is smooth, or it may have soft hairs
    Leaf blade width
    4.5–15 mm
    Leaf ligule length
    1–7 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 fused together and form a closed tube except (possibly) at the very top
    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
    • aquatic
    • wetlands
    New England state
    • Connecticut
    • Maine
    • Massachusetts
    • New Hampshire
    • Vermont
    Specific habitat
    • edges of wetlands
    • in lakes or ponds
    • in rivers or streams
    • man-made or disturbed habitats
    • marshes
    • meadows or fields
    • river or stream floodplains
  • Stem, shoot, branch
    Plant height
    50–200 cm
    Roots at lower stem nodes
    yes
    Stem hairs
    the stem is nearly to completely hairless
    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)
    Stem thickness at base
    8–12 mm

Wetland Status

Occurs only in wetlands. (Wetland indicator code: OBL)

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
unranked (S-rank: SNR)

var. grandis

Massachusetts
unranked (S-rank: SNR)

Native to North America?

Yes

Sometimes Confused With

Glyceria maxima:
leaves with blades mostly 8-18 mm wide and minutely scabrous sheaths and upper glumes mostly 3-4 mm long (vs. G. grandis, with leaves with blades mostly 4.5-12 mm wide and smooth sheaths, and upper glumes 1.5-2.7 mm long).
Glyceria striata:
spikelets 2–4.5 mm long, glumes obtuse, the first one 0.5–1 mm long, and new cauline leaves 5–10 per stem (vs. G. grandis, with spikelets 4–6.5 mm long, glumes acute, the first one 1.2–1.9 mm long, and new cauline leaves 3–6 per stem).

Synonyms

  • Glyceria maxima ssp. grandis (S. Wats.) Hultén
  • Glyceria maxima var. americana (Torr.) Boivin
  • Panicularia grandis (S. Wats.) Nash

Family

Poaceae

Genus

Glyceria

Notes on Subspecies and Varieties in New England

Our variety is Glyceria grandis S. Wats. var. grandis.

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Information from Dichotomous Key of Flora Novae Angliae

5.  Glyceria grandis S. Wats. var. grandis N

American manna grass. Glyceria maxima (Hartman) Holmb. ssp. grandis (S. Wats.) Hultén; 
 G. maxima (Hartman) Holmb. var. americana (Torr.) Boivin; Panicularia grandis (S. Wats.) Nash • CT, MA, ME, NH, VT; also reported from RI by George (1992), but specimens are unknown. Shallow water of pools, lakes, and streams, ditches, wetland edges.