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Paspalum setaceum — slender beadgrass

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Facts

There are three varieties of slender beadgrass in New England. The most widespread (Paspalum setaceum var. muhlenbergii) is present in all New England states except Maine. Another (P. setaceum var. psammophilum) is found primarily on the coastal plain of Connecticut, Massachusetts and Rhode Island. The third (P. setaceum var. setaceum) is also found in Connecticut, Massachusetts and Rhode Island.

Habitat

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

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
New England state
  • Connecticut
  • Massachusetts
  • New Hampshire
  • Rhode Island
  • Vermont
Leaf blade width
1.5–10.2 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
1.4–2.5 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 ligule length
0.2–0.5 mm
Show all 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
    1–2
    Floret types within spikelet
    • NA
    • there are at least two distinct forms of florets within one spikelet
    Glume relative length
    one or both glumes are as long or longer than all of the florets
    Glume veins
    • 0
    • 1
    • 3
    • 5
    Inflorescence axis orientation
    • the inflorescence axis is arched or curved outward
    • 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 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 has pairs (or trios) of spikelets that are similar to each other in structure and size, with at least one of the spikelets on a stalk
    • the inflorescence is branched and the branches all 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 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
    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
    1.4–2.5 mm
    Spikelets spiny
    the spikelets do not appear spiny
  • Leaves

    Leaf auricles
    the leaves do not have auricles
    Leaf blade hairs
    the leaf blade is hairy
    Leaf blade width
    1.5–10.2 mm
    Leaf ligule length
    0.2–0.5 mm
    Leaf ligule type
    the leaf ligule is in the form of a membrane
    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
    New England state
    • Connecticut
    • Massachusetts
    • New Hampshire
    • Rhode Island
    • Vermont
    Specific habitat
    • edges of forests
    • man-made or disturbed habitats
    • meadows or fields
  • Stem, shoot, branch

    Stem orientation
    • the stems are upright
    • the stems trail along the ground or on other plants through most or all of their length
    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)

Wetland status

Usually occurs in non-wetlands, but occasionally in wetlands. (Wetland indicator code: FACU)

In New England

Distribution

Connecticut
present
Maine
absent
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
unranked (S-rank: SNR)

var. muehlenbergii

Vermont
rare (S-rank: S2)

var. muhlenbergii

Massachusetts
widespread (S-rank: S5)
New Hampshire
uncommon (S-rank: S3), W (code: W)

var. psammophilum

Connecticut
historical (S-rank: SH), special concern, extirpated (code: SC*)
Massachusetts
rare to uncommon (S-rank: S2S3)
Rhode Island
extremely rare (S-rank: S1), concern (code: C)

var. setaceum

Massachusetts
uncommon (uncertain) (S-rank: S3?)

Subspecies and varieties

Variety psammophilum is known from CT, MA, RI and occurs primarily on the coastal plain. Variety muhlenbergii is known from CT, MA, NH, RI, VT. Variety setaceum is known from CT, MA, RI.

From Flora Novae Angliae dichotomous key

2.  Paspalum setaceum Michx. N

slender beadgrass. 2a. Paspalum psammophilum Nash; 2b. Paspalum ciliatifolium Michx. 
var. muhlenbergii (Nash) Fern.; P. muhlenbergii Nash; P. pubescens Muhl. • CT, MA, NH, RI, VT. Sandy fields, roadsides, and forest edges.

1a.  Plants prostrate to wide-spreading; leaf blades pubescent with short, soft hairs shorter than 1.5 mm … 2a. P. setaceum var. psammophilum (Nash) D. Banks

1b.  Plants erect to spreading; leaf blades pubescent, at least in part, with stiffer hairs longer than 1.5 mm (shorter hairs may also be present)

2a.  Spikelets 1.8–2.5 ×1.5–2 mm; lower lemmas usually with a midvein 
 … 2b. P. setaceum var. muhlenbergii (Nash) D. Banks

2b.  Spikelets 1.4–1.9 ×1.1–1.6 mm; lower lemmas usually without a midvein 
 … 2c. P. setaceum var. setaceum

Variety psammophilum is known from CT, MA, RI and occurs primarily on the coastal plain. Variety muhlenbergii is known from CT, MA, NH, RI, VT. Variety setaceum is known from CT, MA, RI.

Native to North America?

Yes

Sometimes confused with

Paspalum laeve:
spikelets 2.3–3.3 mm long, solitary at each node, and ligules 1.5–3.8 mm long (vs. P. setaceum, with spikelets 1.4–2.5 mm long, paired at each node, and ligules 0.2–0.5 mm long).

Synonyms

  • Paspalum psammophilum Nash

Family

Poaceae

Genus

Paspalum