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Montana Field Guide

Montana Field Guides

Tall Dropseed - Sporobolus compositus
Other Names:  Sporobolus asper

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Species of Concern
Native Species

Global Rank: G5
State Rank: SH
(see State Rank Reason below)
State Threat Score: No Known Threats
C-value:


Agency Status
USFWS:
USFS:
BLM:


 

External Links

State Rank Reason (see State Rank above)
Known in Montana from 3 collections; a 1939 collection near Ekalaka, a 1957 collection from Fort Keogh Livestock and Range Laboratory and a 1980 collection from Bighorn County.
 
General Description
Perennial. Stems 30–80 cm. Leaves: blades 2–4 mm wide; throat with a tuft of hairs. Inflorescence a contracted panicle 5–15 cm long, mostly enclosed in leaf sheath. Spikelets 4–6 mm long. Lemmas 3–6 mm long (Lavin in Lesica et al. 2012. Manual of Montana Vascular Plants. BRIT Press. Fort Worth, TX).

Phenology
Mature fruit in August.

Diagnostic Characteristics
Tall Dropseed - Sporobolus compositus, SOC
*Habit: Perennial.
*Panicle: Contracted (appressed), but much longer than wide and usually partially enclosed in the leaf sheath.
*Stem: Base is erect.
*Spikelets: 3 mm or more long. Both glumes are not as long or longer than the lemma.

Alkali Dropseed - Sporobolus airoides
*Habit: Perennial.
*Panicle: Diffuse, greater than 4 centimeters long, and about as long as wide and usually fully exerted from the leaf sheath.
*Stem: Base is decumbent.
*Spikelets: 2-2.5 mm long.

Sand Dropseed - Sporobolus cryptandrus
*Habit: Perennial.
*Panicle: Contracted (appressed), greater than 4 centimeters long, and much longer than wide and enclosed in an arcuate leaf sheath.
*Stem: Base is erect.
*Spikelets: 2.5 mm or shorter. Both glumes are not as long or longer than the lemma.

Small Dropseed - Sporobolus neglectus, SOC
*Habit: Annual.
*Panicle: Contracted (narrow), less than 4 cm long, and usually partially enclosed by the leaf sheath.
*Spikelets: 2-3 mm long.

Prairie Dropseed - Sporobolus heterolepis, not documented in Montana
*Habit: Perennial.
*Panicle: Open, greater than 4 centimeters long, and much longer than wide and usually entirely exerted from the leaf sheath.
*Spikelets: At least one of the glumes is as long or longer than the lemma.

Species Range
Montana Range Range Descriptions

Native
 


Range Comments
Collected in Carter County; sporadic throughout most of North America (Lavin in Lesica et al. 2012. Manual of Montana Vascular Plants. BRIT Press. Fort Worth, TX).

Observations in Montana Natural Heritage Program Database
Number of Observations: 13

(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
Open forests and grasslands on the plains.
Predicted Suitable Habitat Model

This species has a Predicted Suitable Habitat Model available.

To learn how these Models were created see mtnhp.org/models

Threats or Limiting Factors
STATE THREAT SCORE REASON
Threat impact not assigned because threats are not known (MTNHP Threat Assessment 2021).

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?
    • Brey, C.W. 1998. Epidemiology of wheat curl mite (Aceria tosichella K.) and wheat streak mosaic virus on feral grass species and effect of glyphosate on wheat curl mite dispersal. Ph.D. Dissertation. Bozeman, MT: Montana State University. 136 p.
    • Flora of North America Editorial Committee. 2003. Flora of North America North of Mexico. Vol. 25. Magnoliophyta: Commelinidae (in part): Poaceae, part 2. Oxford Univ. Press, New York. xxv + 781 pp.
    • Lesica, P., M.T. Lavin, and P.F. Stickney. 2022. Manual of Montana Vascular Plants, Second Edition. Fort Worth, TX: BRIT Press. viii + 779 p.
  • Web Search Engines for Articles on "Tall Dropseed"
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Citation for data on this website:
Tall Dropseed — Sporobolus compositus.  Montana Field Guide.  .  Retrieved on , from