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Dichanthelium acuminatum — hairy rosette-panicgrass

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Facts

Hairy rosette-panicgrass typically inhabits open places with thin or sandy soils. There are six subspecies present in New England, of which five are widespread and one is restricted and regionally rare.

Habitat

Anthropogenic (man-made or disturbed habitats), cliffs, balds, or ledges, grassland, meadows and fields, mountain summits and plateaus, ridges or ledges, shores of rivers or lakes, talus and rocky slopes, woodlands

New England distribution

Adapted from BONAP data

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North America distribution

Adapted from BONAP data

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Characteristics

Habitat
  • terrestrial
  • wetlands
New England state
  • Connecticut
  • Maine
  • Massachusetts
  • New Hampshire
  • Rhode Island
  • Vermont
Leaf blade width
2–12 mm
Inflorescence branches
the flowers are attached to branches rather than to the main axis of the inflorescence
Spikelet length
1.3–2.1 mm
Glume relative length
one or both glumes are as long or longer than 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 sheath hair type
  • there are hairs on the surface of the leaf sheath, and some of the hairs have blisters at their bases
  • 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 ligule length
1–1.5 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 awn length
    0 mm
    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
    • 1
    • 3
    • 5
    • 7 or more
    Glumes per spikelet
    2
    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 crowding
    the panicle is somewhat to very congested (crowded), and the branches may not be clearly seen without close inspection
    Inflorescence length
    35–120 mm
    Inflorescence length to width ratio
    1.3–4
    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
    8–120 mm
    Inforescence position
    • the spikelets are mainly carried at the end of the stem
    • the spikelets are mainly found at the nodes, in the axils of leaves, along 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 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
    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 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 below the glumes
    Spikelet length
    1.3–2.1 mm
    Spikelet number per node
    0
    Spikelet pedicel
    the spikelets have pedicels
    Spikelet shape
    • the spikelets are elliptic (widest in the middle, tapering to the ends) in profile
    • the spikelets are obovate (egg-shaped but with the widest point above the middle) in profile
    Spikelet width
    0.8–1 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 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 does not have a groove on it

  • Growth form

    Horizontal rooting stem
    no
    Lifespan
    the plant lives more than two years
    Rhizomes
    no
    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 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 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
    3–12 cm
    Leaf blade texture
    the leaf blade is rough and sandpapery
    Leaf blade width
    2–12 mm
    Leaf ligule length
    1–1.5 mm
    Leaf ligule type
    the leaf ligule is in the form of 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 hair type
    • there are hairs on the surface of the leaf sheath, and some of the hairs have blisters at their bases
    • 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
    • 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
    • cliffs, balds, or ledges
    • grasslands
    • man-made or disturbed habitats
    • meadows or fields
    • mountain summits and plateaus
    • ridges or ledges
    • shores of rivers or lakes
    • talus or rocky slopes
    • 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
    Plant height
    15–75 cm
    Roots at lower stem nodes
    no
    Stem hairs
    • the stem has hairs on it
    • the stem is nearly to completely hairless
    Stem node number
    4–7
    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
    Stem thickness at base
    At least 1 mm

Wetland status

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

In New England

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.

ssp. acuminatum

Massachusetts
extremely rare (uncertain) (S-rank: S1?)
Rhode Island
concern (code: C)

ssp. columbianum

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

ssp. fasciculatum

Massachusetts
widespread (S-rank: S5)

ssp. implicatum

Massachusetts
fairly widespread (S-rank: S4)

ssp. lindheimeri

Massachusetts
widespread (S-rank: S5)
Vermont
extremely rare (uncertain) (S-rank: S1?)

ssp. spretum

Massachusetts
fairly widespread (S-rank: S4)

Subspecies and varieties

Dichanthelium acuminatum (Sw.) Gould & C.A. Clark ssp. acuminatum is known from MA, RI and is of regional conservation concern.D. acuminatum ssp. columbianum (Scribn.) Freckmann & Lelong is known from CT, MA, ME, NH, RI, VT.D. acuminatum ssp. fasciculatum (Torr.) Freckmann & Lelong is known from CT, MA, ME, NH, RI, VT.D. acuminatum ssp. implicatum (Scribn.) Freckmann & Lelong is known from CT, MA, ME, NH, RI, VT.D. acuminatum ssp. lindheimeri (Nash) Freckmann & Lelong is known from CT, MA, ME, NH, RI, VT.D. acuminatum ssp. spretum (J.A. Schultes) Freckmann & Lelong is known from CT, MA, ME, NH, RI.

From Flora Novae Angliae dichotomous key

1.  Dichanthelium acuminatum (Sw.) Gould & C.A. Clark NC

hairy rosette-panicgrass. 1a. Dichanthelium columbianum (Scribn.) Freckmann; Panicum acuminatum Sw. var. columbianum (Scribn.) Lelong; P. columbianum Scribn.; P. oricola 
 A.S. Hitchc. & Chase; P. sabulorum (Lam.) Gould & C.A. Clark var. thinium (A.S. Hitchc. & 
Chase) C.F. Reed; 1b. Dichanthelium lanuginosum (Ell.) Gould; Panicum acuminatum Sw.; 
P. auberne Ashe; P. lanuginosum Ell.; 1c. Dichanthelium lanuginosum (Ell.) Gould var. lindheimeri (Nash) Fern.; D. lindheimeri (Nash) Gould; Panicum lanuginosum Ell. var. lindheimeri (Nash) Fern.; P. lanuginosum Ell. var.  septentrionale (Fern.) Fern.; 1d. Dichanthelium acuminatum (Sw.) Gould & C.A. Clark var. densiflorum (Rand & Redf.) 
Gould & C.A. Clark; Panicum nitidum Lam. var. densiflorum Rand & Redf.; P. spretum
J.A. Schultes; 1e. Dichanthelium languidum(Hitchc. & Chase) Wipff; Dichanthelium lanuginosum (Ell.) Gould var. fasciculatum (Torr.) 
Spellenberg; Panicum languidum Hitchc. & Chase; P. lanuginosum Ell. var. fasciculatum (Torr.) Fern.; P. lanuginosum Ell. var. tennesseense (Ashe) Gleason; P. tennesseense Ashe; P. unciphyllum forma prostratum Fern.; 1f. Panicum lanuginosum Ell. var.  implicatum (Scribn.) Fern.; P. acuminatum Sw. var. implicatum (Scribn.) C.F. Reed; P. meridionale Ashe • CT, MA, ME, NH, RI, VT. Frequently in open places with sandy 
or thin soils, such as shorelines, fields, roadsides, disturbed places, grasslands, balds, ledges, rocky slopes, and woodlands.

1a.  Stems and leaf sheaths densely puberulent (the sheaths sometimes less so) with 
minute, non-pustulose-based hairs, with scattered longer hairs also usually present 
(i.e., the pubescence of two types) [Fig. 209] 
… 1a. D. acuminatum ssp. columbianum (Scribn.) Freckmann & Lelong

1b.  Stems and leaf sheaths glabrous or pubescent, when pubescent, most or all of the hairs elongate (i.e., exceeding 1 mm) and usually pustulose-based, not of two types (except in the rare ssp. acuminatum and sometimes in ssp. fasciculatum)

2a.  Leaf sheaths densely pubescent with long hairs that originate usually from small pustules and also with minute hairs underneath the longer ones (i.e., the pubescence of two types); leaf blades softly pubescent with velvety hairs on the abaxial surface 
1b. D. acuminatum ssp. acuminatum

2b.  Leaf sheaths glabrous or pubescent, the hairs all long (i.e., of one type), and originating from rather conspicuous pustules or not at all pustulose-based (sometimes with hairs of two types in the common ssp. fasciculatum, but the short hairs usually scarce); leaf blades variously glabrous, puberulent, or pilose on the abaxial surface, but generally not feeling velvety to the touch

3a.  Leaf sheaths glabrous or pubescent with non-pustulose-based hairs (though the margins of the sheaths often ciliate near the apex) [Fig. 210]

4a.  Terminal panicle 2.5–7 cm tall, less than 2 times as tall as wide, open; leaf blades and sheaths yellow-green, with few or no pustulose-based cilia near the base; spikelets usually obovoid … 1c. D. acuminatum ssp. lindheimeri (Nash) Freckmann & Lelong

4b.  Terminal panicle 4–12 cm tall, 2–4 times as tall as wide, somewhat congested; leaf blades and sheaths green or purple-tinged, often with conspicuous, pustulose-based cilia near the base; spikelets usually ellipsoid 
… 1d. D. acuminatum ssp. spretum (J.A. Schultes) Freckmann & Lelong

3b.  Leaf sheaths pubescent with pustulose-based hairs

5a.  Leaf blades glabrous or pilose on the adaxial surface with hairs shorter than 
3 mm, usually 6–12 mm wide, spreading or ascending; spikelets 1.5–2 mm long … 1e. D. acuminatum ssp. fasciculatum (Torr.) Freckmann & Lelong

5b.  Leaf blades pilose on the adaxial surface with hairs 3–6 mm long, usually 2–6 mm wide, erect to ascending; spikelets 1.1–1.5 mm long … 1f. D. acuminatum ssp. implicatum (Scribn.) Freckmann & Lelong

Subspecies columbianum is known from CT, MA, ME, NH, RI, VT. Subspecies acuminatum is known from MA, RI and is of regional conservation concern. Subspecies lindheimeri is known from CT, MA, ME, NH, RI, VT. Subspecies spretum is known from CT, MA, ME, NH, RI. Subspecies fasciculatum is known from CT, MA, ME, NH, RI, VT. Subspecies implicatum is known from CT, MA, ME, NH, RI, VT.

1×10. Dichanthelium acuminatum × Dichanthelium oligosanthes → Dichanthelium ×‌scoparioides (Ashe) Mohlenbrock is a rare rosette panicgrass hybrid in New England known from CT, MA, VT. It resembles D. ovale due to the long, projecting ligule of hairs mostly 2–3 mm long and the spikelets 2.2–2.4 mm long. However, the stems and sheaths are pubescent with short (mostly 1–1.5 mm long) and sparse, spreading-ascending hairs (or these parts ± glabrous; rather than having long, spreading or ascending to appressed hairs in D. ovale). The hybrid is further characterized by leaf blades mostly 6–10 mm wide. It was also reported from RI by Kartesz (1999); however, this record was erroneously based on Collins (1928), who did not report this hybrid from RI. The epithet scopariodes may not properly refer to this hybrid.

Native to North America?

Yes

Sometimes confused with

Dichanthelium boreale:
ligule of hairs up to 1 mm long and spikelets mostly 2-2.2 mm long (vs. D. acuminatum, with a ligule of hairs 1-5 mm long and spikelets 1.3-2.1 mm long).
Dichanthelium ovale:
spikelets 2.1–2.6 mm long, and sheaths pubescent with hairs 2–4 mm long (vs. D. acuminatum, with spikelets 1.3–2.1 mm long, and sheaths glabrous or with hairs usually shorter than 2 mm).

Synonyms

  • Dichanthelium lanuginosum (Ell.) Gould var. fasciculatum (Torr.) Spellenberg
  • Panicum lanuginosum Ell. var. fasciculatum (Torr.) Fern.
  • Panicum lanuginosum Ell. var. tennesseense (Ashe) Gleason
  • Panicum subvillosum Ashe
  • Panicum tennesseense Ashe

Family

Poaceae

Genus

Dichanthelium