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• Poaceae
• Poaceae Group 5
• Leymus
• Leymus mollis

Leymus mollis — American lyme grass

Facts

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

• 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

  • neither glume is quite as long as all of the florets
  • one or both glumes are as long or longer than 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

From the dichotomous key of Flora Novae Angliae