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Astragalus knightii
(Knight's milkvetch)
[taxon report][distribution map][photos][line drawing]
Family: Fabaceae
Scientific Name: Astragalus knightii Barneby
Synonyms: None
Vernacular Name: Knight's milkvetch
R-E-D Code: 2-1-3
Description: Tufted perennial herb; stems numerous, ascending, 1-5 cm long, arising from a taproot; herbage gray-strigose with dolabriform hairs; stipules of the lower nodes connate; leaves pinnately compound, 2.5-8.5 cm long; stalks long, wiry, and sometimes persistent on the caudex; leaflets 9-15, narrowly elliptic or ovate-elliptic, 2-8 mm long; calyx 3-4 mm long, bell-shaped; petals whitish, lilac-tinged along the margins, lower petal purple tipped, banner bent upward 45 degrees, 5-6 mm long; pods pendulous, narrowly obovoid-ellipsoid, turgid or almost bladdery, 8-14 mm long, 4-6 mm wide, red spotted. Flowers May to early June.
Similar Species: Astragalus ceramicus can be distinguished from A. knightii by the presence of thread-like rhizomes and the absence of a taproot.
Distribution: New Mexico, Sandoval County, Mesa Prieta.
Habitat: Rimrock ledges of Dakota Formation sandstone in piņon-juniper woodland; 1,750-1,800 m (5,700-5,900 ft).
Remarks: Presently known only from the Mesa Prieta area of the middle Rio Puerco drainage. The specific epithet honors Paul Knight who discovered this species while working as a botanist for the State of New Mexico.
Conservation Considerations: Some populations are small and could be seriously impacted by road development, pipelines and mining activities. This species is not otherwise threatened by the current land uses within its habitats.
Important Literature (*Illustration):
Barneby, R.C. 1983. A new Astragalus from sandstone rimrock in New Mexico. Brittonia 35:109-110.
Isely, D. 1998. Native and naturalized Leguminosae (Fabaceae) of the United States. Monte L. Beane Life Science Museum, Brigham Young University, Provo, Utah.
*New Mexico Native Plants Protection Advisory Committee. 1984. A handbook of rare and endemic plants of New Mexico. University of New Mexico Press, Albuquerque.
Information Compiled By: Ken Heil, Joey Herring, 1999
Agency Status:
