Astragalus missouriensis var. humistratus (Pagosa Milkvetch)

Photograph by Cecilia Alexander at polyploid.net (2009)

Family

FABACEAE

Scientific Name with Author

Astragalus missouriensis Nuttall var. humistratus Isley

Synonyms

NONE

Common Name

Pagosa Milkvetch

Agency Status
USFWS	State of NM	USFS	BLM	Navajo Nation	State Rank	Global Rank	NMRPTC Status
		SEN, SCC			S1	G5T2	R

Rare Plant Conservation Scorecard Summary
Overall Conservation Status	Documented Threats	Actions Needed
UNDER CONSERVED	No Information	Status surveys on abundance, distribution and threats

To download the Scorecard click here.

Counties

RIO ARRIBA

Description

Plants strongly caulescent; stems dolabriform pubescent, prostrate, 1-1.5(-2) dm long; leaves 5-14 cm long; leaflets mostly 11-19, obovate or elliptic, 5-15 mm long, 2-3 mm wide; stipules lower connate; inflorescences subumbels with 9-12 ascending or spreading, narrow flowers; flowers pea-like; calyx tube cylindric, often dark-pigmented, mostly 6-9 mm long, corolla pink-purple, wing petal tips white; fruit ascending, divergent or humistrate, sessile, unilocular or subunilocular, persistent, dorsiventrally compressed at maturity, mostly 12-25 mm long, 6-9 mm wide, fleshy, often dull-reddish. Flowers in May.

Similar Species

Variety humistratus is distinguished from variety missouriensis and variety amphibolus by its longer, prostrate stems and connate lower stipules. The pods of variety amphibolus are usually abruptly upturned at the tip and sometimes deciduous. The pods of variety humistratus and variety missouriensis are straight and persistent.

Distribution

New Mexico, northern Rio Arriba County; adjacent Colorado, Archuleta and Hinsdale counties.

Habitat

Soils derived from the Mancos and Lewis formations. Openings in ponderosa pine, Gambel oak, and upper piñon-juniper woodlands at 2,150-2,345 m (7,050-7,700 ft).

Comments

Astragalus missouriensis var. humistratus is a very narrow endemic known only from a few locations in Colorado and three locations in New Mexico. In Colorado it is often found with Townsendia glabella, another narrow endemic.

Conservation Considerations

An inventory of potential habitat in New Mexico is needed to determine if current land uses pose a threat to this plant. Residential growth and development are the main threats in Colorado.

References

Isley, D. 1998. Native and naturalized Leguminosae (Fabaceae) of the United States. Monte L. Bean Life Science Museum, Brigham Young University, Provo, Utah.

*Decker, K. 2006. Astragalus missouriensis Nutt. var. humistratus Isely (Missouri milkvetch): a technical conservation assessment. [Online]. USDA Forest Service, Rocky Mountain Region. Available: http://www.fs.fed.us/r2/projects/scp/assessments/astragalusmissouriensisvarhumistratus.pdf [accessed May 2007].

Isely D. 1983. New combinations and two new varieties in Astragalus, Orophaca, and Oxytropis (Leguminosae). Systematic Botany 8:420-426.

Information Compiled By

Kenneth D. Heil 2007

For distribution maps and more information, visit Natural Heritage New Mexico