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Montana Field Guides

Least Spikerush - Eleocharis acicularis

Native Species

Global Rank: G5
State Rank: SNR
C-value: 4


Agency Status
USFWS:
USFS:
BLM:


 

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General Description
Slenderly rhizomatous perennial. Stems ascending to erect, 1–25 cm, tufted. Spikelet 2–7 mm long with 3 to 15 flowers. Scales purplish with a green midrib and hyaline margins, 1.5–2.5 mm long. Flowers: bristles 0 to 4, exceeding the achene; stigmas 3. Achenes grey, honeycombed, obovoid, ca. 1 mm long with a flattened, triangular tubercle (Lesica et al. 2012. Manual of Montana Vascular Plants. BRIT Press. Fort Worth, TX).

Diagnostic Characteristics
Eleocharis acicularis - Least Spikerush
*Life Cycle: Perennial; rhizomatous.
*Stems: 1-25 cm tall.
*Achene: gray, honeycombed, obovoid, and about 1.0 mm long.
*Scales: longer than the achene, 1.5-2.5 mm long.
*Stigma: 3

Eleocharis bella - Delicate Spikerush, SOC
*Life Cycle: Annual; lacks rhizomes.
*Stems: 1-8 cm tall.
*Achene: whitish, honeycombed, obovoid, nearly round in cross-section, 0.5-1.0 mm long.
*Scales: about 1.0 mm long.
*Stigma: 3

Eleocharis ovata - Ovate Spikerush
*Life Cycle: Annual; lacks rhizomes.
*Achene: gray to brown, obovate, lenticular, and about 1.5 mm long.
*Scales: longer than the achene,2-2.5 mm long.
*Stigma: 2

Eleocharis elliptica - Slender Spikerush
*Life Cycle: Perennial; rhizomatous.
*Stems: 10-14 cm tall.
*Achene: yellow, honeycombed, obovoid, and 1.0-1.5 mm long.
*Scales: longer than the achene, 2-3 mm long.
*Stigma: 3

Eleocharis rostellata - Beaked Spikerush, SOC
*Life Cycle: Perennial; tufted.
*Stems: 10-80 cm long, erect or arching and able to root at the tip to form new plants.
*Achene: green-gray, obovoid, and 2-6 mm long.
*Scales: longer than the achene, about 2.0 mm long.
*Stigma: 3

Species Range
Montana Range

Year-round
 


Range Comments
Circumboreal to S. America (Lesica et al. 2012. Manual of Montana Vascular Plants. BRIT Press. Fort Worth, TX).

Observations in Montana Natural Heritage Program Database
Number of Observations: 165

(Click on the following maps and charts to see full sized version) Map Help and Descriptions
Relative Density

Recency

 

(Observations spanning multiple months or years are excluded from time charts)



Habitat
Muddy shores or shallow water on margins of ponds, lakes, streams, ditches; plains, valleys, montane (Lesica et al. 2012. Manual of Montana Vascular Plants. BRIT Press. Fort Worth, TX).

References
  • Literature Cited AboveLegend:   View Online Publication
    • Lesica, P., M.T. Lavin, and P.F. Stickney. 2012. Manual of Montana Vascular Plants. Fort Worth, TX: BRIT Press. viii + 771 p.
  • Additional ReferencesLegend:   View Online Publication
    Do you know of a citation we're missing?
    • Culver, D.R. 1994. Floristic analysis of the Centennial Region, Montana. M.Sc. Thesis. Montana State University, Bozeman. 199 pp.
    • Hildebrand, B. D. 1979. Habitat requirements of molting Canada Geese at Lima Reservoir, Montana. M.Sc. Thesis. Bozeman, MT: Montana State University. 79 p.
    • Hollenbeck, R.R. 1974. Growth rates and movements within a population of Rana pretiosa pretiosa Baird and Girard in south central Montana. Ph.D. Dissertation. Bozeman, Montana: Montana State University. 66 p.
    • Horpestad, A.A. 1969. Factors affecting the distribution and abundance of aquatic macrophytes in parts of the Madison, Firehole and Gibbon Rivers. M.Sc. Thesis. Bozeman, MT: Montana State University. 88 p.
    • Jones, W. W. 1901. Preliminary flora of Gallatin County. M.S. Thesis. Bozeman, MT: Montana State College. 78 pp.
    • Miller, M.G. 1980. The influence of habitat features on waterfowl productivity on stock reservoirs in south Valley County, Montana. M.Sc. Thesis. Bozeman, MT: Montana State University. 43 p.
    • Mundinger, J.G. 1975. The influence of rest-rotation grazing management on waterfowl production on stock-water reservoirs in Phillips County, Montana. M.Sc. Thesis. Bozeman, MT: Montana State University. 100 p.
    • Rasmussen, S.M. 1968. Composition and structure of macrophyte vegetation of the Firehole River, Yellowstone National Park as related to physical and chemical factors. M.Sc. Thesis. Bozeman, MT: Montana State University. 44 p.
  • Web Search Engines for Articles on "Least Spikerush"
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Citation for data on this website:
Least Spikerush — Eleocharis acicularis.  Montana Field Guide.  .  Retrieved on , from