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• Poaceae
• Poaceae Group 4
• Bromus
• Bromus japonicus

Bromus japonicus — Japanese brome

Facts

Japanese brome is a Eurasian annual, widely introduced in North America and considered a noxious weed on rangelands and prairies where it competes with native perennials for water and nutrients. In New England it is found in fields, roadsides and disturbed sites.

Habitat

Anthropogenic (man-made or disturbed habitats), meadows and fields

Characteristics

• Flowers

  Anther length

  Up to 1.5 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

  6–12

  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

  Glume relative length

  neither glume is quite as long as all of the florets

  Glume shape

  the glume is V-shaped in cross-section

  Glume veins

  • 3
  • 5
  • 7 or more

  Glumes per spikelet

  2

  Inflorescence arrangement

  the spikelets are uniform

  Inflorescence axis orientation

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

  Inflorescence branch length

  5–10 cm

  Inflorescence branch roughness

  the inflorescence branches are somewhat to very rough

  Inflorescence branches

  the flowers are attached to branches rather than to the main axis of the inflorescence

  Inflorescence branches coming off the lowest stem node

  3–5

  Inflorescence crowding

  the panicle is somewhat to very spread out, with clearly-evident branches

  Inflorescence length

  100–220 mm

  Inflorescence length to width ratio

  1.7–2.5

  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

  40–130 mm

  Inforescence position

  the spikelets are mainly carried at the end of the stem

  Lemma awn base

  the awn is attached at the upper half 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

  8–13 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 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

  NA

  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 split into two or more points

  Lemma vein number

  7 or more

  Lemma vein orientation

  the veins on the lemma come together near the tip

  Lower glume length

  4.5–7 mm

  One or more florets

  there is more than one floret per spikelet

  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 an 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

  20–40 mm

  Spikelet number per node

  Up to 0

  Spikelet pedicel

  the spikelets have pedicels

  Spikelet shape

  the spikelets are lanceolate (lance-shaped, widest below the middle and tapering narrowly to the ends) in profile

  Spikelet width

  8–10 mm

  Spikelets per panicle branch

  1–4

  Spikelets spiny

  the spikelets do not appear spiny

  Tip of glume

  • the tip of the glume is divided into two or more points
  • the tip of the glume is not divided (though it may have an awn on it)

  Upper glume length

  5–8 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

  Groove on seed

  the caryopsis has a groove running most of its length

  Seed length

  7–8 mm

• Growth form

  Horizontal rooting stem

  no

  Lifespan

  the plant lives only a single year or less

  Rhizomes

  no

  Roots

  there are only slender roots on the plant

• Leaves

  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
  • the leaf blade is hairy

  Leaf blade length

  10–20 cm

  Leaf blade texture

  the leaf blade is rough and sandpapery

  Leaf blade width

  2–4 mm

  Leaf ligule length

  1–2.2 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 hairs on the surface of the leaf sheath, but the hairs do not have blisters at their bases
  • there are no hairs on the surface of the leaf sheath

  Leaf sheath hairs

  there are 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

  • Connecticut
  • Maine
  • Massachusetts
  • New Hampshire
  • Vermont

  Specific habitat

  • man-made or disturbed habitats
  • meadows or fields

• Stem, shoot, branch

  Hairs at nodes

  • the stem nodes are hairless or they have very sparse hairs
  • the stem nodes have hairs that stand out at a shallow angle, or they curve downwards

  Plant height

  22–70 cm

  Stem hairs

  • the stem has hairs on it
  • 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

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