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Montana Field Guide

Montana Field Guides

Northwestern Thelypody - Thelypodium paniculatum
Other Names:  Thelypodium sagittatum var. crassicarpum

Species of Concern

Global Rank: G2
State Rank: SH
* (see State Rank Reason below)

Agency Status
USFWS:
USFS:
BLM:
MNPS Threat Rank:
C-value:

External Links






State Rank Reason (see State Rank above)
Known only from an 1899 collection in Beaverhead County, although Dorn (1984) also reports it for Madison County.
 
General Description
Northwestern thelypody is an herbaceous biennial or short-lived perennial with solitary, simple or branched stems that are 3-7 dm high and arising from a taproot. Its lower leaves are 4-10 cm long and have petioles and narrowly lance-shaped, entire-margined blades. The upper stem leaves are 2-6 cm long and lance-shaped with basal wings that clasp the stem. Foliage is glabrous and has a thin, waxy coating. Flowers are borne on ascending stalks in cylindric inflorescences that are up to 35 cm long when mature. Each flower has 4 separate sepals that are 5-8 mm long, 4 separate, lavendar petals that are 10-16 mm long and 2-6 mm wide, and 4 long and 2 short stamens. The ascending, straight, cylindrical capsules, or siliques, are 25-40 mm long and 1.3-2.3 mm wide.

Phenology
Flowering occurs in June.

Diagnostic Characteristics
Thelypodium sagittatum is very similar but has petals that are only 1-3 mm wide and fruits that are less than 1.3 mm wide.

Species Range
Unknown/Undetermined
 


Range Comments
This species is known from ID, MT, WY and CO (Kartesz in prep. 2012). It occurs in eastern ID, southwestern MT, in Beaverhead County (Montana NHP 1999) but evidently not Madison County as included by Dorn (1984); western and southern WY in 8 counties (Park, Teton, Sublette, Lincoln, Uinta [T. paniculatum type locality], Fremont, Carbon and Platte),and CO Jackson County (Weber and Wittmann 1996a) and perhaps the northwest in Moffat County (Colorado State University Herbarium 1999, but not Weber and Wittmann 1992, 1996b).

Summary of Observations Submitted for Montana
Number of Observations: 1

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

Recency

 

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



Habitat
Northwestern thelypody grows in wet sedge meadows where the water level may cover basal portions of the plant. It appears to favor meadows and stream bottoms that remain wet for most of the season. Two localities in Yellowstone National Park are in very wet sedge meadows. In contrast, Thelypodium sagittatum, grows in alkaline meadows that are often dry, but may be wet in the early part of the season (Al-Shehbaz 1973).

Ecological Systems Associated with this Species

Ecology
Northwestern thelypody has lightweight seeds that are probably very easily distributed (Al-Shehbaz 1973). Wind may be an important factor in their dispersal in open habitats such as deserts, flats and open slopes, but the action of rain wash is perhaps equally if not more important (Al-Shehbaz 1973). Flooding is likely to be a major means of seed dispersal for species growing along streamsides, creek beds and river banks, and may also be important for those found in meadows (Al-Shehbaz 1973).

Management
Based on available habitat information, this species could be vulnerable to riparian grazing or hydrologic changes.

References
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Citation for data on this website:
Northwestern Thelypody — Thelypodium paniculatum.  Montana Field Guide.  .  Retrieved on , from