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Small-headed Tarweed - Madia minima
Other Names:  Hemizonella minima

Potential Species of Concern
Native Species

Global Rank: G4
State Rank: S3S4
State Threat Score: No Known Threats

Agency Status


External Links

General Description
Small-headed tarweed is an annual with stems up to 10 cm (4 in) high, and long, slender branches from near the base. The (usually) opposite leaves, 1-2 cm long, are linear and long-pointed. Foliage is sparsely hairy below and glandular above. Small clusters of flower heads occur on the ends of the short terminal branches. Each head has 3-5 glandular, involucral bracts, 2-4 mm high, enclosing a ray flower. The yellow rays are minute, and there is a solitary, yellow disk flower surrounded by small bracts. The curved seeds (achenes), enclosed in the glandular bracts, resemble a section of orange.

Flowering May to June, fruiting June to July.

Diagnostic Characteristics
The low, long-branched habit with small heads is diagnostic.

Species Range
Montana Range Range Descriptions


Range Comments
BC south to CA, NV, ID and MT (Lesica et al. 2012. Manual of Montana Vascular Plants. BRIT Press. Fort Worth, TX).

Observations in Montana Natural Heritage Program Database
Number of Observations: 39

(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)

Vernally moist, often moss-covered soil on impermeable bedrock in openings of coniferous forest in the valleys and montane zone.
Predicted Suitable Habitat Model

This species has a Predicted Suitable Habitat Model available.

To learn how these Models were created see

  • 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?
    • 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.
    • Schassberger, L.A. 1991. Rare plant inventory of the East Pioneer Mountains. Prepared for the USDA Forest Service, Region 1, Beaverhead National Forest. Montana Natural Heritage Program, Helena, MT. 55 pp.
    • Schassberger, L.A. and J.S. Shelly. 1990. Sensitive plant surveys in the Bull River and adjacent drainages, USDA Forest Service, Region 1, Kootenai National Forest. Unpublished report. Montana Natural Heritage Program, Helena, MT. 60 pp.
    • Tiedemann, A. 1972. Soil properties and nutrient availability in tarweed communities of central Washington. Journal of Range Management 25(6):438-443.
  • Web Search Engines for Articles on "Small-headed Tarweed"
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Citation for data on this website:
Small-headed Tarweed — Madia minima.  Montana Field Guide.  .  Retrieved on , from