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• Panicum virgatum

Panicum virgatum — switch panicgrass

Facts

Switch panicgrass is a North American native perennial drought-tolerant grass that is a palatable forage grass and is planted domestically and worldwide for range and wildlife habitat improvement. It is one of the main species being considered as a biofuel crop, but calculations of carbon emissions savings need to include the effects of widespread land-use conversion if this species begins to be widely grown for biofuels.

Habitat

Anthropogenic (man-made or disturbed habitats), brackish or salt marshes and flats, marshes, meadows and fields, shores of rivers or lakes, wetland margins (edges of wetlands)

Characteristics

• Flowers

  Anther number

  3

  Awn on glume

  the glume has no awn

  Bristles below spikelets

  no

  Floret lower bract texture

  the lemma is hard and firm

  Floret number

  2

  Floret types within spikelet

  there are at least two distinct forms of florets within one spikelet

  Glume awn length

  0 mm

  Glume keel

  the glume keels are smooth and hairless

  Glume relative length

  one or both glumes are as long or longer than all of the florets

  Glume shape

  the glume is flat or curved in cross-section

  Glume veins

  • 5
  • 7 or more

  Glumes per spikelet

  2

  Inflorescence arrangement

  the spikelets are uniform

  Inflorescence axis orientation

  the inflorescence axis is straight

  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 crowding

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

  Inflorescence length

  100–550 mm

  Inflorescence length to width ratio

  2.5–2.8

  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

  40–200 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

  NA

  Lemma base length

  0 mm

  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 hairless

  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 a simple point, with or without an awn (long narrow extension ending in a point)

  Lemma vein number

  • 3
  • 5
  • 7 or more

  Lower glume length

  1.8–3.2 mm

  Lower glume relative length

  the lower glume is one third to three quarters as long as the upper glume

  One or more florets

  • there is more than one floret per spikelet
  • there is one floret per spikelet

  Palea length

  3–3.5 mm

  Palea relative length

  palea is one half to fully as long as lemma

  Reproductive system

  some flowers on the plant have both carpels and stamens, while other flowers have only one type of reproductive organ (polygamous)

  Spikelet axis tip

  there is no extension of the spikelet axis beyond the tip of the spikelet

  Spikelet disintegration

  the spikelet breaks off below the glumes

  Spikelet length

  2.5–8 mm

  Spikelet number per node

  0

  Spikelet pedicel

  the spikelets have pedicels

  Spikelet pedicel length

  0.5–20 mm

  Spikelet shape

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

  Spikelet width

  1.2–2.5 mm

  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

  2.8–8 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

  Seed length

  2–3 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 blade base

  the leaf is tapered gradually to the base

  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

  10–60 cm

  Leaf blade texture

  the leaf blade is rough and sandpapery

  Leaf blade width

  2–15 mm

  Leaf ligule length

  2–6 mm

  Leaf ligule type

  the leaf ligule is in the form of a membrane with fine hairs

  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 hairs

  • there are hairs on the surface of the leaf sheath
  • there are no hairs on the surface of the leaf sheath

• Place

  Habitat

  • terrestrial
  • wetlands

  New England state

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

  Specific habitat

  • brackish or salt marshes and flats
  • edges of wetlands
  • man-made or disturbed habitats
  • marshes
  • meadows or fields
  • shores of rivers or lakes

• Stem, shoot, branch

  Hairs at nodes

  the stem nodes are hairless or they have very sparse hairs

  Plant height

  40–300 cm

  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

  3–5 mm

Wetland status

Occurs in wetlands or non-wetlands. (Wetland indicator code: FAC)

New England distribution and conservation status

From the dichotomous key of Flora Novae Angliae