Prairie Spiderwort - Tradescantia occidentalis
(see State Rank Reason below)
MNPS Threat Rank
State Rank Reason (see State Rank above)
See rank details.
- Details on Status Ranking and Review
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.
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.
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.
Score0-1 - Low to Moderate Vulnerability.
Raw Conservation Status Score
3 to 6 total points scored out of a possible 19.
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.
MT to MN south to AZ, NM, TX and LA (Lesica 2012. Manual of Montana Vascular Plants. BRIT Press. Fort Worth, TX).
Observations in Montana Natural Heritage Program Database
Number of Observations:
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Map Help and Descriptions
(Observations spanning multiple months or years are excluded from time charts)
- Additional ReferencesLegend: View Online Publication
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- Anderson, N.L. 1962. Grasshopper-vegetation relationships on Montana grasslands. Ph.D Dissertation. Bozeman, Montana: Montana State University. 73 p.
- Lesica, P., M.T. Lavin, and P.F. Stickney. 2012. Manual of Montana Vascular Plants. Fort Worth, TX: BRIT Press. viii + 771 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.