Astragalus Peckii aka Peck’s Milkvetch (or just “A. peckii”) is a threatened species listed on the State and Federal list of Threatened and Endangered plants and animals. Link to listing https://www.fs.fed.us/r6/sfpnw/issssp/documents2021/or-p-im-2021-004-2.pdf or click HERE for a local copy.
Astragalus peckii is the only threatened plant species found in Deschutes County and has been seen on TID, BLM and DSL properties in our Area of Concern (AoC) as seen on the survey maps shown later in this document. Astragalus subspecies are found worldwide and have been used as medicines in native cultures. A. Peckii was thought extinct until rediscovered in Deschutes County in 1980. An internet search has not uncovered evidence that A. Peckii has been investigated for its medicinal compounds nor has its genome been completely characterized. Why this plant is able to thrive in the harsh and variable climate of Bull Flat is unknown.
Oregon ODA Astralagus Peckii Profile
The State of Oregon Department of Agriculture has the following profile of Peck’s Milkvetch. https://www.oregon.gov/ODA/shared/Documents/Publications/PlantConservation/AstragalusPeckiiProfile.pdf. Click HERE for a copy if the site is down.
Of specific relevance to the AoC are the following excerpts:
- Range: Peck’s milkvetch occurs east of the Cascades from Cline Buttes south to a few miles south of Chiloquin. Populations can be broadly grouped into three population centers, with the largest concentration occurring along Highway 97 between Sisters and Bend. A second grouping inhabits the barren pumice flats near Chemult, and a southern group occurs in openings in ponderosa pine stands east of Chiloquin.
- Federal status: Species of Concern
- Threats: Urbanization and agricultural development near the towns of Bend and Sisters have historically threatened populations of A. peckii. Currently, disturbance due to off-road vehicle use is probably the greatest threat to persistence of this species, although weed infestations and rapid urban development continue to concern conservation planners.
Astragalus Peckii disturbance Ecology Study – 2008 Final Report
The site to download this document is here: https://vdocument.in/download/astragalus-peckii-disturbance-2008-final-report-ure-ram-t-astragalus-peckii. If the site is down, click HERE for a copy. Note that BLM partially funded and participated in this study and two of the six study sites were within the AoC. Curiously, no maps are included.
Of specific relevance to the AoC is the following excerpt:
Management Recommendations
- Limit the duration and severity of Astragalus peckii exposure to repeated disturbance from logging, ATV use, and livestock grazing. If disturbance occurs, establish a monitoring program to assess its long-term impacts on affected A. peckii populations.
- As burning does not produce a definitive positive or negative impact to survival, growth, and reproduction of A. peckii, sites supporting this species can be included in controlled burns. Monitoring of populations before and after burning would provide additional information on the effect of fire on this species.
- Because seedlings emerge throughout the spring and early summer and exhibit low mortality during the summer months, proposed disturbances (such as logging) should be limited to the winter months to avoid excessive impacts to seedling recruitment.
- During our study visits we noticed increasing weed infestations (knapweed, cheatgrass) in disturbed areas near Sisters. Monitoring of A. peckii populations for encroaching weeds, with treatment if needed, may be required to protect this species from the threats posed by exotic species competition.
- Future monitoring of A. peckii populations should focus on large scale transect sampling methods to assess overall trends in plant density and reproduction, coupled with the tracking of individual plants to garner demographic information. We recommend against continued use of square-meter photoplots for this species.
Astragalus peckii Population Establishment: Developing Protocols for Seed Germination, Seedling Cultivation, and Planting
This thesis was written in 2015 by Tabitha Pearson with the goal of meeting the requirements for a degree of Honors Baccalaureate of Science in Botany. fTWC participated in this study which was performed with Peck’s populations in Bull Flat among others. Of general interest is that this plant has adapted to the harsh and variable environments where it is found. The internet source is: https://scholar.google.com/scholar?q=Demography,+reproductive+ecology,+and+community+analysis+of+Peck%27s+milkvetch&hl=en&as_sdt=0&as_vis=1&oi=scholart. If the site is down, click HERE for a copy.
Mapping:
Plotting the exact areas where Peck’s is located within the AoC has had its roots in differing objectives. In the thesis above, locations are identified in the following two graphics. This site analysis was done to understand the impact of disturbed habitat (Page 38).

The extent of Peck’s plants around Bull Flat Road was identified in the Pearson study as shown below. This graphic is from the slide set accompanying the thesis. Click HERE to see the slide set.

The map below was generated by the DSL as part of the COAMP process and subsequently used for reference in an abandoned land swap between TID and DSL. The map was found appended to the October 9, 2012 Regular Board Meeting Minutes of the Tumalo Irrigation District. The area outlined in blue dotted lines delineates an area of Astragulus Peckii distribution to the north-northwest of the current Tumalo Reservoir. Interestingly, this map got lost in the process of assembling the inventory for Tract #30 and the information was not included in the COAMP plan. The map was later added to the research file after COAMP publication in 2011. Click HERE to go to our DSL page.

The following Google Earth follow-up mapping was done in June 2020 by a qualified participant in the 2015 Pearson study. The purpose was to assess the status of Peck’s Milkvetch along Bull Flat Road as it leaves Sisemore Road.

A walkabout in May of 2022 by three members of fTWC finds A. Peckii in much the same places and concentrations as the above map.
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