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Montana Field Guides

Prairie Spiderwort - Tradescantia occidentalis

Native Species

Global Rank: G5
State Rank: S4
(see State Rank Reason below)
C-value: 4

Agency Status


External Links

State Rank Reason (see State Rank above)
See rank details.
  • Details on Status Ranking and Review
    Prairie Spiderwort (Tradescantia occidentalis) Conservation Status Review
    Review Date = 07/06/2012
    View State Conservation Rank Criteria
    Population Size

    Score1 - Moderate: Generally 10,000-100,000 individuals.

    CommentPopulation size is unknown for Montana, but due to its sparse distribution is estimated to be <100,000 plants.

    Range Extent

    Score0 - Widespread species within Montana (occurs in 5% or more of the state or generally occurring in 6 or more sub-basins.) as well as outside of Montana.

    Area of Occupancy

    Score0-1 - Moderate to High. Occurs in >10 Subwatersheds (6th Code HUC’s), though the species' distribution is not sufficiently documented to place it within one class.

    Environmental Specificity

    Score1 - Moderate: Species is restricted to a specific habitat that is more widely distributed or to several restricted habitats and is typically dependent upon relatively unaltered, good-quality habitat (C Values of 5-7).


    Score0-1 - Stable to Minor Declines:

    CommentTrends are undocumented, but it does not appear that the species has experienced moderate or severe declines.


    Score1 - Medium: 11-30% of the populations are being negatively impacted or are likely to be impacted by one or more activities or agents, which are expected to result in decreased populations and/or habitat quality and/or quantity.

    Intrinsic Vulnerability

    Score0-1 - Low to Moderate Vulnerability.

    Raw Conservation Status Score

    Score 3 to 6 total points scored out of a possible 19.

General Description
Perennial, subsucculent herbaceous plant. Roots both fleshy and succulent. Stems to 60 cm in height. Leaves, green with a whitish bloom, alternate, linear-lanceolate, entire, 6-50 cm in length and 0.2-2.0 cm broad, with sheathing bases. Inflorescence umbellate, subtended by elongate bracts similar to the foliage leaves. Bracts to 60 cm long. Flower stalks, 1-2 cm long, and glandular hairy. Sepals 3, 6-12 mm long, glandular hairy, with purplish margins. Petals 3, blue to rose, broadly ovate, and 7-15 mm long. One flower in each cluster opens each day, and lasts for only a few hours. Stamens six. Fruit a capsule with three locules (sections), each locule producing 3-6 oblong seeds, 2-4 mm long, yellow to dark brown in color.

Our plants are variety occidentalis.

Species Range
Montana Range Range Descriptions


Range Comments
MT to MN south to AZ, NM, TX and LA (Lesica et al. 2012. Manual of Montana Vascular Plants. BRIT Press. Fort Worth, TX).

Observations in Montana Natural Heritage Program Database
Number of Observations: 63

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



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


The following animal species have been reported as pollinators of this plant species or its genus where their geographic ranges overlap: Bombus vagans, Bombus pensylvanicus, and Bombus griseocollis (Colla and Dumesh 2010).

  • Literature Cited AboveLegend:   View Online Publication
    • Colla, S.R. and S. Dumesh. 2010. The bumble bees of southern Ontario: notes on natural history and distribution. Journal of the Entomological Society of Ontario 141:39-68.
    • 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?
    • Anderson, N.L. 1962. Grasshopper-vegetation relationships on Montana grasslands. Ph.D Dissertation. Bozeman, Montana: Montana State University. 73 p.
    • Boggs, K. W. 1984. Succession in riparian communities of the lower Yellowstone River, Montana. M.S. Thesis. Montana State University, Bozeman, 107 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.
    • Seipel, T.F. 2006. Plant species diversity in the sagebrush steppe of Montana. M.Sc. Thesis. Bozeman, MT: Montana State University. 87 p.
    • Wiman, N.G. 2001. Dynamics of leafy spurge (Euphorbia esula L.) infested plant communities influenced by flea beetles in the Aphthona complex (Colepotera: Chrysomelidae). M.Sc. Thesis. Bozeman, MT: Montana State University. 148 p.
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Citation for data on this website:
Prairie Spiderwort — Tradescantia occidentalis.  Montana Field Guide.  .  Retrieved on , from