Scientific Name : Thelypodium paniculatum
Author : A. Nels.
NatureServe Explorer
Common Name : Northwestern Thelypody
Current Research Activities
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Taxonomy
Brassicaceae (mustard family)
=Thelypodium sagittatum var. crassicarpum
Ranks and Status
State Rank : S1
State Rank Reason : Thelypodium paniculatum is known from one historical general record (1903) on private land in Jackson County, and one historical record (1947) in Moffat County, Colorado, USA. Attempts at relocating the historical occurrences have been unsuccessful. This species is ranked S2 in Wyoming and S1 in Idaho and Montana (NatureServe 2023).
U.S. Endangered Species Act : none
Colorado Threatened and Endangered List : none
Other Statuses : SWAP SGIN
Description and Phenology
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 not flattened, and are 25-40 mm long and 1.3-2.3 mm wide.
Look Alikes:
This species is similar to T. sagitatum, but the latter has fruits less than 1.2 mm wide and petals less than 3 mm wide. Thelypodium paniculatum might also be confused with species of Arabis, but those plants have flattened rather than cylindrical siliques.
Phenology:
Flowering and fruiting in June-July (Ackerfield 2012).
Habitat
In Colorado this species is found in meadows and stream bottoms.
Elevation Range:
7,000 - 8,000 feet (2,134 - 2,438 meters)
Distribution
Colorado Endemic:
No
Range:
Thelypodium paniculatum is known from two historical records - one in Moffat County and one in Jackson County Colorado, USA (CNHP 2024). This taxon has also documented from Idaho, Montana, and Wyoming, USA.
Threats and Management Issues
References
- Ackerfield, J. 2015. Flora of Colorado. BRIT Press, Botanical Research Institute of Texas, Fort Worth, TX. 818 pp.
- Al-Shehbaz, I.A. 1973. Biosystematics of Thelypodium. Contributions from the Gray Herbarium of Harvard University 204:3-148.
- Colorado Natural Heritage Program (CNHP). 2025. Biodiversity Tracking and Conservation System (Biotics 5). Colorado Natural Heritage Program, Colorado State University, Fort Collins.
- Flora of North America Editorial Committee (FNA). 2010. Flora of North America north of Mexico. Vol. 7. Magnoliophyta: Salicaceae to Brassicaceae. Oxford University Press, New York. xxii + 797 pp.
- Handwerk, J., L. Grunau, and S. Panjabi. 2015. Colorado Wildlife Action Plan: 2015 Rare Plant Addendum. Colorado Natural Heritage Program, Colorado State University, Fort Collins, Colorado, USA.
- Harrington, H.D. 1954. Manual of the plants of Colorado. Sage Press, Chicago. 666 pp.
- Holmgren, N.H., P.K. Holmgren, and A. Cronquist. 2005. Intermountain flora. Volume 2, part B. Subclass Dilleniidae. The New York Botanical Garden Press. 488 pages.
- Lesica, P. 2003. Conserving globally rare plants on lands administered by the Dillon Office of the Bureau of Land Management. Report to the USDI Bureau of Land Management, Dillon Office. Montana Natural Heritage Program, Helena, MT. 22 pp. plus appendices.
- Montana Field Guide. 2008. Accessed online at: http://fieldguide.mt.gov (August 2008)
- Neely, B., S. Panjabi, E. Lane, P. Lewis, C. Dawson, A. Kratz, B. Kurzel, T. Hogan, J. Handwerk, S. Krishnan, J. Neale, and N. Ripley. 2009. Colorado Rare Plant Conservation Strategy, Developed by the Colorado Rare Plant conservation Initiative. The Nature Conservancy, Boulder, Colorado, 117 pp.
- Rollins, R.C. 1993. The Cruciferae of Continental North America:Systematics of the Mustard Family from the Arctic to Panama. Stanford University Press. Stanford, CA.
- USDA, NRCS. 2022. The PLANTS Database. National Plant Data Team, Greensboro, NC 27401-4901 USA.
- Weber, W. A. and R. C. Wittmann. 2012. Colorado Flora, Eastern Slope, A Field Guide to the Vascular Plants, Fourth Edition. Boulder, Colorado. 555 pp.
