Sporobolus compositus (Poir.) Mer.

rough dropseed

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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

Widespread in the Great Plains and Midwest, rough dropseed is rare in New England. It occurs on a variety of open habitats, mostly with sandy substrates. As with other grassland species, the apparent decline of rough dropseed in New Enlgland may be due to widespread reforestation since the late nineteenth century. There are two varieties present in New England, both of conservation concern. One of them (Sporobolus compositus var. compositus) is found in Connecticut, Massachusetts, Rhode Island and Vermont, while the other (S. compositus var. drummondii) is found only in Maine.

Habitat

Anthropogenic (man-made or disturbed habitats), cliffs, balds, or ledges, coastal beaches (sea beaches), forest edges, grassland, meadows and fields, ridges or ledges, shores of rivers or lakes, talus and rocky slopes

Characteristics

Habitat
  • terrestrial
  • wetlands
New England state
  • Connecticut
  • Maine
  • Massachusetts
  • Rhode Island
  • Vermont
Leaf blade width
1.5–10 mm
Inflorescence branches
  • the flowers are attached to branches rather than to the main axis of the inflorescence
  • there are no branch points between the base of the inflorescence axis and the flowers, or they are not obvious
Spikelet length
4–10 mm
Glume relative length
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 one floret per spikelet
Lemma awn length
0 mm
Leaf ligule length
0.1–0.5 mm
Anther length
1–2 mm
Show All Characteristics
  • Flowers
    Anther length
    1–2 mm
    Anther number
    2–3
    Awn on glume
    the glume has no awn
    Floret lower bract texture
    the lemma is thin and flexible
    Floret types within spikelet
    all the florets within a spikelet are similar
    Glume relative length
    neither glume is quite as long as all of the florets
    Glume veins
    • 0
    • 1
    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
    • there are no branch points between the base of the inflorescence axis and the flowers, or they are not obvious
    Inflorescence length
    50–300 mm
    Inflorescence type (general)
    • the inflorescence is a spike, or is spike-like, lacking obvious branches
    • 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 length
    0 mm
    Lemma awn number
    the lemma has no awn
    Lemma cross-section
    the lemma is flat or rounded if you cut across the midpoint
    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
    1
    One or more florets
    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
    4–10 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
  • Leaves
    Leaf auricles
    the leaves do not have auricles
    Leaf blade width
    1.5–10 mm
    Leaf ligule length
    0.1–0.5 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
  • Place
    Habitat
    • terrestrial
    • wetlands
    New England state
    • Connecticut
    • Maine
    • Massachusetts
    • Rhode Island
    • Vermont
    Specific habitat
    • cliffs, balds, or ledges
    • edges of forests
    • grasslands
    • man-made or disturbed habitats
    • meadows or fields
    • ridges or ledges
    • sea beaches
    • shores of rivers or lakes
    • talus or rocky slopes
  • Stem, shoot, branch
    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
    1–5 mm

Wetland Status

Not classified

New England Distribution and Conservation Status

Distribution

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

Conservation Status

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

Massachusetts
unranked (S-rank: SNR)
Vermont
rare (S-rank: S2), endangered (code: E)

var. compositus

Massachusetts
unranked (S-rank: SNR), #NAME? (code: #NAME?)
Rhode Island
extremely rare (S-rank: S1), concern (uncertain) (code: C*)

var. drummondii

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

Native to North America?

Yes

Sometimes Confused With

Sporobolus clandestinus

Synonyms

  • Sporobolus asper (Beauv.) Kunth

Family

Poaceae

Genus

Sporobolus

Notes on Subspecies and Varieties in New England

Variety compositus is known from CT, MA, RI, VT. Variety drummondii is known from 
ME and is disjunct from other populations of this taxon. Both varieties are of regional conservation concern.

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Information from Dichotomous Key of Flora Novae Angliae

2.  Sporobolus compositus (Poir.) Mer. NC

rough dropseed. 2a. Sporobolus asper (Beauv.) Kunth; 2b. Sporobolus asper (Beauv.) Kunth var. pilosus (Vasey) A.S. Hitchc.; S. drummondii (Trin.) Vasey • CT, MA, ME, RI, VT. River shores, banks, and outcrops, lakeshore headlands, sandy fields and coastal beaches, dry openings and barrens.

1a.  Reproductive stems 2–5 mm thick; upper sheaths 2.6–6 mm wide; inflorescences with 30–90 spikelets per cm2 when pressed … 2a. S. compositus var. compositus

1b.  Reproductive stems 1–2 (–2.5) mm thick; upper sheaths 0.8–2.5 mm wide; inflorescences with 16–36 spikelets per cm2 when pressed 
 … 2b. S. compositus var. drummondii (Trin.) Kartesz & Gandhi

Variety compositus is known from CT, MA, RI, VT. Variety drummondii is known from 
ME and is disjunct from other populations of this taxon. Both varieties are of regional conservation concern.