Leymus mollis (Trin.) Hara

American lyme 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

American lyme grass is a common dune grass from Atlantic and Pacific coast beaches. Its bluish-green foliage and stout spikelets that contain more than one floret distinguish it from the common beach grass, Ammophila breviligulata, with which it often co-occurs. Dune grasses possess special adaptations that allow them to tolerate and grow faster in response to repeated burial by sand. As such, they are critical for stabilizing dunes against erosion.

Habitat

Coastal beaches (sea beaches)

Characteristics

Habitat
terrestrial
New England state
  • Maine
  • Massachusetts
  • New Hampshire
Leaf blade width
3–15 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
15–34 mm
Glume relative length
  • both glumes are as long or longer than all of the florets
  • 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
0.2–2.5 mm
Anther length
4–9 mm
Show All Characteristics
  • Flowers
    Anther length
    4–9 mm
    Anther number
    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
    3–6
    Floret types within spikelet
    all the florets within a spikelet are similar
    Glume awn length
    0 mm
    Glume keel
    • the glume keels are rough or hairy
    • the glume keels are smooth and hairless
    Glume relative length
    • both glumes are as long or longer than all of the florets
    • neither glume is quite as long as all of the florets
    Glume shape
    • the glume is V-shaped in cross-section
    • the glume is flat or curved in cross-section
    Glume veins
    • 3
    • 5
    Glumes per spikelet
    2
    Inflorescence axis hairs
    the inflorescence axis is hairy but not rough or sand-papery feeling
    Inflorescence axis orientation
    • the inflorescence axis is arched or curved outward
    • the inflorescence axis is straight
    Inflorescence branch length
    0 cm
    Inflorescence branch roughness
    NA
    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
    0
    Inflorescence crowding
    NA
    Inflorescence length
    120–340 mm
    Inflorescence length to width ratio
    12–17
    Inflorescence type (general)
    the inflorescence is a spike, or is spike-like, lacking obvious branches
    Inflorescence type (specific)
    the inflorescence is a spike (a long unbranched stem with flowers along it that lack stalks)
    Inflorescence width
    10–20 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 cross-section
    the lemma is V-shaped if you cut across the midpoint
    Lemma hairs
    the lemma has fine hairs between the veins
    Lemma keel hairs
    the keel of the lemma is rough, or has fine hairs
    Lemma marginal vein hairs
    the marginal vein of the lemma has fine hairs on it
    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 tapers to a narrow point (it may or may not also have an awn or teeth at the tip)
    Lemma vein number
    5
    Lemma vein orientation
    the veins on the lemma stay roughly parallel throughout
    Lower glume length
    24–13 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 length
    10–13 mm
    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
    15–34 mm
    Spikelet number per node
    Up to 3
    Spikelet pedicel
    the spikelets do not have pedicels
    Spikelet pedicel length
    0 mm
    Spikelet position
    NA
    Spikelet shape
    the spikelets are elliptic (widest in the middle, tapering to the ends) in profile
    Spikelet width
    5–7 mm
    Spikelets per panicle branch
    0
    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
    13–34 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 above the middle
    • the upper glume is widest at or below the middle
  • Fruits or seeds
    Groove on seed
    the caryopsis has a groove running most of its length
  • 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 large or prominent tufts of leaves at the base of the flowering stem
    Leaf auricles
    the leaves have auricles
    Leaf basal lobe hairy
    the lobes at the base of the leaf blades are hairless
    Leaf blade base
    the leaf is tapered gradually to the base
    Leaf blade cross-section
    • the leaf blade is clearly folded or rolled inwards
    • 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
    10–94 cm
    Leaf blade texture
    the leaf blade is rough and sandpapery
    Leaf blade width
    3–15 mm
    Leaf ligule length
    0.2–2.5 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 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
    Orientation of topmost leaf
    the flag leaf is held upright, or at less than a 45 degree angle out from the stem
  • Place
    Habitat
    terrestrial
    New England state
    • Maine
    • Massachusetts
    • New Hampshire
    Specific habitat
    sea beaches
  • Stem, shoot, branch
    Plant height
    50–170 cm
    Stem hairs
    the stem has hairs on it
    Stem node number
    3–4
    Stem orientation
    the stems are upright
    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
    3–6 mm

Wetland Status

Usually occurs in non-wetlands, but occasionally in wetlands. (Wetland indicator code: FACU)

New England Distribution and Conservation Status

Distribution

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

Conservation Status

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

Maine
unranked (S-rank: SNR)
Massachusetts
unranked (S-rank: SNR)

ssp. mollis

Massachusetts
extremely rare (S-rank: S1), endangered (code: E)
New Hampshire
extremely rare (S-rank: S1), endangered (code: E)

Native to North America?

Yes and no (some introduced)

Sometimes Confused With

Ammophila breviligulata:
inflorescence a highly congested panicle, spikelets with only 1 floret, and lemmas not pubescent over the abaxial surface (vs. L. mollis, with the inflorescence a spike and spikelets with 3-6 florets, and lemmas pubescent over the abaxial surface).

Synonyms

  • Elymus arenarius L. var. villosus E. Mey.
  • Elymus capitatus Scrib.
  • Elymus mollis Trin.
  • Leymus arenarius (L.) Hochst. ssp. mollis (Trin.) Tzvelev

Family

Poaceae

Genus

Leymus

Notes on Subspecies and Varieties in New England

Our variety is Leymus mollis (Trin.) Hara var. mollis.

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Information from Dichotomous Key of Flora Novae Angliae

1.  Leymus mollis (Trin.) Hara var. mollis N

American lyme grass. Elymus arenarius L. var. villosus E. Mey.; E. capitatus Scrib.; E. mollis Trin.; Leymus arenarius (L.) Hochst. ssp. mollis (Trin.) Tzvelev • MA, ME, NH. Atlantic coast beaches.