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Astragalus missouriensis

Astragalus missouriensis

Astragalus missouriensis variety amphibolus

Astragalus missouriensis variety amphibolus (Missouri Milkvetch)
Fabaceae (Pea Family)

Semi-desert. Woodlands, shrublands, openings. Spring.
Above:
Lone Mesa State Park, May 20, 2016.
Left: Near Narraguinnep Canyon, May 8, 2009 and
Near Lone Mesa State Park, May 1, 2015.

Click to read about the Astragalus genus..


Astragalus missouriensis

Astragalus missouriensis

Astragalus missouriensis variety amphibolus (Missouri Milkvetch)
Fabaceae (Pea Family)

Semi-desert. Woodlands, shrublands, openings. Spring.
Near Narraguinnep Canyon, May 8, 2009 and
Lone Mesa State Park, May 20, 2016.

Astragalus missouriensis inhabits dry hillsides and meadows from about 5,000 to 8,000 feet elevation in Pinyon/Juniper woods and Sagebrush meadows. 

Astragalus missouriensis is found from Alberta, Saskatchewan, and Manitoba southward to Texas.  Welsh points out that it is "remarkably uniform" in its characteristics throughout this entire area  --  except in the Four Corners region where it has "undergone taxonomically significant... morphological differentiation".  This differentiation may separate the various varieties of Astragalus missouriensis, but it is still quite difficult to distinguish Astragalus missouriensis variety amphibolus from Astragalus chamaeleuce and Astragalus amphioxys.  All three are found in the Four Corners region.

In 1818 Thomas Nuttall named and described Astragalus missouriensis from a specimen collected by Bradbury.  Twentieth century Astragalus expert Rupert Barneby, named and described variety amphibolus in 1947 from specimens collected near Mancos, Colorado by Baker, Earle, and Tracy.

Astragalus missouriensis often occurs in masses as shown on the next page of photographs. Click to see.

Astragalus missouriensis

Astragalus missouriensis variety amphibolus (Missouri Milkvetch)
Fabaceae (Pea Family)

Semi-desert. Woodlands, shrublands, openings. Spring.
Blackrock Canyon, Navajo Reservation, Arizona, May 12, 2007.

Seed pods are sessile and are usually ascending (as pictured).  They are ellipsoid, 15-30 mm long, 5-9 mm thick, somewhat curved, hairy, pointed on one end, and moderately compressed.  Compare these seed pods, which are persistent, with Astragalus amphioxys seed pods which quickly fall off the plant.

 

Range map © John Kartesz,
Floristic Synthesis of North America

State Color Key

Species present in state and native
Species present in state and exotic
Species not present in state

County Color Key

Species present and not rare
Species present and rare
Species extirpated (historic)
Species extinct
Species noxious
Species exotic and present
Native species, but adventive in state
Questionable presence

Range map for Astragalus missouriensis

Astragalus missouriensis variety amphibolus

Range map for Astragalus missouriensis variety amphibolus