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Montana Field Guides

Prairie Dropseed - Sporobolus heterolepis

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Not Documented

Global Rank: G5
State Rank: SNA
(see State Rank Reason below)

Agency Status


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State Rank Reason (see State Rank above)
Sporobolus heterolepis is not documented as occurring in Montana. This plant has been 'reported' for Montana, but as of 2019 no specimens have been validated. The Grasses of Montana (Booth 1972) included it, but the publication did not provide species' distributions. This was the basis for its inclusion in the Vascular Plants of Montana (Dorn 1984); however, Dorn found no specimens (personal communication). Sporobolus heterolepis occurs in neighboring North and South Dakota states, and is the basis for its inclusion in the Manual of Montana Vascular Plants (Lesica et al. 2012). A conservation status rank is not applicable (SNA) because this plant is not known to occur in Montana.
General Description
This description is adapted from the Flora of the Great Plains (McGregor et al. 1986).

PLANTS:Perennial plants of 40-95 cm tall. Culms are erect, slender, and glabrous.

LEAVES: Blades are 7-31 cm long, 1.4-2.4 mm wide, flat or slightly involute, glabrous to scabrous, and somewhat keeled. Leaf sheaths are slightly keeled, glabrous or the lower one's pubescent. Ligules are 0.1-0.3 mm long and apically fringed.

INFLORESCENCE: Panicle is open, 11-22 cm long, and usually well exerted above the leaf sheath. Primary branches spread while secondary branches are often more or less appressed. Spikelets are 1(2)-flowered, greyish. Glumes are membranous. Lower glume is (1.2-)1.8-4.5 mm long, 1-nerved or nerveless. Upper glume is (2.4-)3.2-6 mm long. Lemmas are 3.2-4.2 mm long, blunt to acute, 1-nerved. Paleas are about equal to or longer than lemmas. Anthers are (1.1-)1.7-3 mm long, dark.

Diagnostic Characteristics
Prairie Dropseed - Sporobolus heterolepis, not documented in Montana
*Panicle: Open, but 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.

Tall Dropseed - Sporobolus compositus, SOC
*Panicle: Contracted (appressed), but much longer than wide and usually partially enclosed in the leaf sheath.
*Spikelets: Both glumes are not as long or longer than the lemma.

Range Comments
Saskatchewan east to Quebec in Canada south to North Dakota, Wyoming, Colorado and New Mexico east to Texas, Louisiana, Missouri, Ohio, and Michigan in the U.S. (Barkworth in Flora of North America 2003).

Open woods and upland or lowland prairies in the Great Plains (McGregor et al. 1986).

  • Literature Cited AboveLegend:   View Online Publication
    • Booth, W. E. 1972. Grasses of Montana. Unpublished manual, 64 pp.
    • Dorn, R. D. 1984. Vascular Plants of Montana. Cheyenne, WY: Mountain West Publishing. 276 pp.
    • 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. 2012. Manual of Montana Vascular Plants. Fort Worth, TX: BRIT Press. viii + 771 p.
    • McGregor, R.L. (coordinator), T.M. Barkley, R.E. Brooks, and E.K. Schofield (eds). 1986. Flora of the Great Plains: Great Plains Flora Association. Lawrence, KS: Univ. Press Kansas. 1392 pp.
  • Additional ReferencesLegend:   View Online Publication
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    • Harvey, S.J. 1990. Responses of steppe plants to gradients of water soil texture and disturbance in Montana, U.S.A. Ph.D. Thesis. Bozeman, MT: Montana State University. 34 p.
    • 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.
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Citation for data on this website:
Prairie Dropseed — Sporobolus heterolepis.  Montana Field Guide.  .  Retrieved on , from