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Montana Field Guide

Montana Field Guides

Slender Thelypody - Thelypodium sagittatum

Species of Concern
Native Species

Global Rank: G4
State Rank: S2
(see State Rank Reason below)
State Threat Score: Unknown
C-value: 6

Agency Status


External Links

State Rank Reason (see State Rank above)
Known from numerous occurrences in extreme southwestern Montana.
General Description
Slender Thelypody is an herbaceous biennial or short-lived perennial with solitary, simple or branched stems that are 3-8 dm high and arising from a taproot. The lower leaves are 6-20 cm long and have petioles and broadly lance-shaped, entire-margined blades. The upper leaves are smaller, narrowly arrow-shaped, and they lack petioles. Foliage is glabrous or nearly so and has a thin, waxy coating. Flowers are densely clustered on ascending stalks in cylindric inflorescences that expand greatly when in fruit. Each flower has 4 separate sepals that are 3-7 mm long, 4 separate, lavendar petals that are 7-14 mm long and 1-3 mm wide, and 4 long and 2 short stamens. The ascending, straight, cylindric siliques are 18-53 mm long and less than 1 mm wide.

Flowering and fruiting from the end of May to mid-July.

Diagnostic Characteristics
Only the typic subspecies is in Montana. This taxa is similar to T. paniculatum, but the latter has fruits that are greater than 1.3 mm wide and petals that are greater than 2.5 mm wide. T. sagittatum might also be confused with species of Arabis, but those plants have flattened rather than cylindrical siliques.

Species Range
Montana Range Range Descriptions


Range Comments
Southeastern WA to CA, east to MT and WY.

Observations in Montana Natural Heritage Program Database
Number of Observations: 35

(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)

Moist, alkaline meadows, often with greasewood or shrubby cinquefoil, in the valley to montane zones.
Predicted Suitable Habitat Model

This species has a Predicted Suitable Habitat Model available.

To learn how these Models were created see

Ecological Systems Associated with this Species

Threats or Limiting Factors
Reported threats to Montana's populations of Slender Thelypody are currently assigned as unknown. Potential threats due to livestock trampling and grazing are negligible according to reported data (MTNHP Threat Assessment 2021).

  • Additional ReferencesLegend:   View Online Publication
    Do you know of a citation we're missing?
    • Al-Shehbaz, I. A. 1973. The biosystematics of the genus Thelypodium (Cruciferae). Contributions from the Gray Herbarium No. 204:3-148.
    • Haglund, B.M. 1972. Ecological effects of weather modification, Bangtail Ridge, Bridger Range, Montana: relationships of pocket gophers (Thomomys talpoides) to time of snow melt. M.Sc. Thesis. Bozeman, Montana: Montana State University. 26 p.
    • Lesica, P., M.T. Lavin, and P.F. Stickney. 2012. Manual of Montana Vascular Plants. Fort Worth, TX: BRIT Press. viii + 771 p.
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Citation for data on this website:
Slender Thelypody — Thelypodium sagittatum.  Montana Field Guide.  .  Retrieved on , from