Dichanthelium dichotomum (L.) Gould

forked rosette-panicgrass

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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

Forked rosette-panicgrass is widespread in New England. It is found in dry to moist soils of woodlands, rocky forests and sandy roadsides, or in wet soils of swamps, wetland margins and other wet sites. There are three subspecies, one of which (Dichanthelium dichotomum ssp. mattamuskeetense) is found only in Massachusetts and Rhode Island, and is rare and protected.

Habitat

Anthropogenic (man-made or disturbed habitats), bogs, cliffs, balds, or ledges, forests, meadows and fields, shores of rivers or lakes, swamps, wetland margins (edges of wetlands), woodlands

Characteristics

Habitat
  • terrestrial
  • wetlands
New England state
  • Connecticut
  • Maine
  • Massachusetts
  • New Hampshire
  • Rhode Island
  • Vermont
Leaf blade width
5–14 mm
Inflorescence branches
the flowers are attached to branches rather than to the main axis of the inflorescence
Spikelet length
1.5–2.5 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
  • there is one floret per spikelet
Lemma awn length
0 mm
Leaf ligule length
0–1 mm
Show All Characteristics
  • Flowers
    Anther number
    0–3
    Awn on glume
    the glume has no awn
    Bristles below spikelets
    no
    Floret lower bract texture
    the lemma is hard and firm
    Floret number
    1–2
    Floret types within spikelet
    • NA
    • there are at least two distinct forms of florets within one spikelet
    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
    • 1
    • 3
    • 5
    • 7 or more
    Inflorescence arrangement
    the spikelets are uniform
    Inflorescence axis orientation
    the inflorescence axis is straight
    Inflorescence branches
    the flowers are attached to branches rather than to the main axis of the inflorescence
    Inflorescence length
    30–120 mm
    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
    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 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 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
    One or more florets
    • there is more than one floret per spikelet
    • there is one floret per spikelet
    Palea relative length
    palea is one half to fully as long as lemma
    Spikelet axis tip
    there is no extension of the spikelet axis beyond the tip of the spikelet
    Spikelet length
    1.5–2.5 mm
    Spikelets spiny
    the spikelets do not appear spiny
    Upper glume shape
    the upper glume is widest at or below the middle
  • Growth form
    Lifespan
    the plant lives more than two years
    Roots
    the plant has a root mass with a hardened top
  • Leaves
    Basal leaves
    the plant has large or prominent tufts of leaves at the base of the flowering stem
    Leaf auricles
    the leaves do not have auricles
    Leaf blade base
    • the leaf blade cuts in abruptly to the narrower base, or has rounded lobes on either side of the base (heart-shaped)
    • the leaf blade is rounded in to a narrower base, or the blade cuts in abruptly to the narrower base
    • the leaf is tapered gradually to the base
    Leaf blade width
    5–14 mm
    Leaf ligule length
    0–1 mm
    Leaf ligule type
    the leaf ligule is in the form of fine hairs
    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
    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
    • wetlands
    New England state
    • Connecticut
    • Maine
    • Massachusetts
    • New Hampshire
    • Rhode Island
    • Vermont
    Specific habitat
    • bogs
    • cliffs, balds, or ledges
    • edges of wetlands
    • forests
    • man-made or disturbed habitats
    • meadows or fields
    • shores of rivers or lakes
    • swamps
    • woodlands
  • 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
    Stem spacing
    the stems grow close together in compact clusters or tufts

Wetland Status

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

New England Distribution and Conservation Status

Distribution

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

Conservation Status

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

Connecticut
widespread (S-rank: S5)
Massachusetts
unranked (S-rank: SNR)
Vermont
uncommon (S-rank: S3)

ssp. dichotomum

Massachusetts
widespread (S-rank: S5)

ssp. mattamuskeetense

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

var. mattamuskatense

Rhode Island
historical (S-rank: SH), state historical (code: SH)

Native to North America?

Yes

Sometimes Confused With

Dichanthelium boreale:
upper-most stem leaf usually erect or ascending, spikelets pubescent, and nodes of stem glabrous (vs. D. dichotomum, with upper-most stem leaf usually spreading, spikelets glabrous or pubescent, 1.5-2.5 mm long, and nodes of stem glabrous or the lower nodes retrorse-pubescent).

Synonyms

  • Panicum barbulatum Michx.
  • Panicum dichotomum L.

Family

Poaceae

Notes on Subspecies and Varieties in New England

Subspecies dichotomum is known from CT, MA, ME, NH, RI, VT. Subspecies mattamuskeetense is known from MA, RI. Both of these subspecies are normally found in dry-mesic to xeric soils, but ssp. mattamuskeetense is occasionally associated with small and/or seasonal wetlands. Subspecies mattamuskeetense is of regional conservation concern. Subspecies microcarpon is known from CT, MA, RI and is usually found in wet-mesic to hydric soils.

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Information from Dichotomous Key of Flora Novae Angliae

7.  Dichanthelium dichotomum (L.) Gould NC

forked rosette-panicgrass.  7a. Panicum barbulatum Michx.; P. dichotomum L.;  7b. Panicum clutei Nash; P. dichotomum L. var. mattamuskeetense (Ashe) Lelong; P. mattamuskeetense Ashe; 7c. Dichanthelium microcarpon (Muhl. ex Ell.) Mohlenbrock; Panicum microcarpon Muhl. ex Ell.; P. nitidum Lam. var.  ramulosum Torr. • CT, MA, ME, NH, RI, VT. Mesic to xeric soils of woodlands, rocky forests, balds, and sandy roadsides, often with Quercus and/or Carya, or in wet-mesic to hydric soils of swamps, wetland edges, low fields, stream banks, pond shores, and bog edges. Reports of Dichanthelium dichotomum ssp. lucidum (Ashe) Freckmann & Lelong from New England are based on specimens of D. dichotomum ssp. dichotomum (specimens at CONN!, GH!, MASS!, NEBC!).

1a.  Lower nodes glabrous or infrequently sparsely pubescent; leaf blades usually 5–7 mm wide, slightly narrowed or constricted near the base … 7a. D. dichotomum ssp. dichotomum

1b.  Lower nodes pubescent with retrorsely oriented hairs; leaf blades (5–) 7–14 mm wide, not or only scarcely narrowed or constricted near the base

2a.  Spikelets 1.8–2.5 mm long, pubescent; leaf sheaths and blades moderately to densely velutinous … 7b. D. dichotomum ssp. mattamuskeetense (Ashe) Freckmann & Lelong

2b.  Spikelets 1.5–1.8 mm long, usually glabrous; leaf sheaths and blade surfaces ± glabrous to sparsely pubescent 
 … 7c. D. dichotomum ssp. microcarpon (Muhl. ex  Ell.) Freckmann & Lelong

Subspecies dichotomum is known from CT, MA, ME, NH, RI, VT. Subspecies mattamuskeetense is known from MA, RI. Both of these subspecies are normally found in dry-mesic to xeric soils, but ssp. mattamuskeetense is occasionally associated with small and/or seasonal wetlands. Subspecies mattamuskeetense is of regional conservation concern. Subspecies microcarpon is known from CT, MA, RI and is usually found in wet-mesic to hydric soils.