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• Elymus riparius

Elymus riparius — eastern riverbank wild-rye

Facts

Eastern riverbank wild-rye grows in the alluvial soils in woods and thickets (riparian zone) along larger streams. It occasionally forms hybrids with other wild-rye (Elymus) species.

Habitat

Forests, shores of rivers or lakes

Characteristics

• Flowers

  Anther length

  2–2.7 mm

  Anther number

  3

  Awn on glume

  the glume has an awn

  Bristles below spikelets

  no

  Floret lower bract texture

  the lemma is thin and flexible

  Floret number

  2–4

  Floret types within spikelet

  all the florets within a spikelet are similar

  Glume awn length

  0–18 mm

  Glume keel

  NA

  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 flat or curved in cross-section

  Glume veins

  3

  Glumes per spikelet

  2

  Inflorescence arrangement

  the spikelets are uniform

  Inflorescence axis hairs

  • the inflorescence axis is rough and feels like sand-paper
  • the inflorescence axis is smooth and has no hairs

  Inflorescence axis orientation

  • the inflorescence axis bends downwards or hangs
  • the inflorescence axis is arched or curved outward

  Inflorescence branch length

  0 cm

  Inflorescence branch roughness

  NA

  Inflorescence branches

  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

  70–250 mm

  Inflorescence length to width ratio

  3.5–6.3

  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

  20–40 mm

  Inforescence position

  the spikelets are mainly carried at the end of the stem

  Lemma awn base

  the awn is attached right at the tip of the lemma

  Lemma awn coiled

  • the lemma awn is coiled at least one half turn
  • the lemma awn is straight or twisted, but not coiled one half turn

  Lemma awn length

  15–35 mm

  Lemma awn number

  the lemma has one awn on it

  Lemma awn orientation

  • the awn of the lemma is straight
  • the awn of the lemma on dried or older plants is curved or bent outwards

  Lemma cross-section

  the lemma is flat or rounded if you cut across the midpoint

  Lemma hairs

  • the lemma has fine hairs between the veins
  • the lemma is hairless between the veins

  Lemma keel hairs

  NA

  Lemma marginal vein hairs

  • the marginal vein of the lemma has fine hairs on it
  • 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 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

  9–17 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

  6–9 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

  10–20 mm

  Spikelet number per node

  2–3

  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
  • the spikelets are oblong (rectangular, but with rounded ends) in profile

  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

  9–17 mm

  Upper glume relative length

  the upper glume is more than one half as long as the lowest lemma

• Fruits or seeds

  Groove on seed

  the caryopsis has a groove running most of its length

• Growth form

  Horizontal rooting stem

  no

  Lifespan

  the plant lives more than two years

  Rhizomes

  no

  Roots

  there are only slender roots on the plant

• 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 hairs

  the leaf blade is hairless, but it may have tiny prickles that give it a sand-papery feel

  Leaf blade texture

  the leaf blade is rough and sandpapery

  Leaf blade width

  5–25 mm

  Leaf ligule length

  Up to 1 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 color and persistence

  the leaf sheathes are reddish-brown and disintegrate or become shredded in older leaves

  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 outward at more than a 45 degree angle from the stem, or it curves downwards from the horizontal
  • the flag leaf is held upright, or at less than a 45 degree angle out from the stem

• Place

  Habitat

  terrestrial

  New England state

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

  Specific habitat

  • forests
  • shores of rivers or lakes

• Stem, shoot, branch

  Hairs at nodes

  the stem nodes are hairless or they have very sparse hairs

  Plant height

  70–160 cm

  Roots at lower stem nodes

  • no
  • yes

  Stem hairs

  the stem is nearly to completely hairless

  Stem node number

  5–10

  Stem orientation

  the stems are upright

  Stem spacing

  the stems grow close together in compact clusters or tufts

Wetland status

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

New England distribution and conservation status

From the dichotomous key of Flora Novae Angliae