Southwest Colorado Wildflowers, Astragalus cottamii and eastwoodiae

The Astragalus genus is large and complex. In Colorado Flora, Western Slope William Weber lists over five dozen species with many sub-species. The new Flora of the Four Corners lists fifty-eight species and several dozen varieties of Astragalus in the Four Corners drainage of the San Juan River. In Intermountain Flora Arthur Cronquist lists 156 species and 122 varieties. World-wide there are about 1600 species.

Astragalus species are difficult to identify and it is the seed pod, not the flower, that is often crucial in the identification process.

The common name, "Locoweed", is applied not to one plant but to many members of the Astragalus genus, for many of these plants absorb toxic soil substances, especially selenium, which cause grazing animals a variety of serious ailments. Further complicating the common name: some people use the name "Locoweed" not only for Astragalus but also for another Pea genus, Oxytropis. And, making common names even more confusing, many Astragalus also carry the common name of "Milk Vetch" (easily confused with other Peas known as "Vetch"). These common names are so confusing that they really should not be used (except in whispers to close friends).

The genus was named by Linnaeus in 1753 and the word "Astragalus" means "ankle bone" in Greek. It is an ancient Greek plant name perhaps given because of the seed shape in some members of the Astragalus genus or, the authors of Intermountain Flora conjecture, because the Greeks used rattling bones for dice and the sound made is similar to the rattling of dry Astragalus seeds in the pod.

Synonym: Astragalus cottamii. Astragalus monumentalis.
Fabaceae (Pea Family)

Semi-desert. Openings. Spring.
New Mexico, April 24, 2007.

Astragalus cottamii, A. desperatus, A. monumentalis, and A. naturitensis are similar in their habitat, size, flower color, pod size, and scarcity. All are easily overlooked. A. cottamii is found only in the Four Corners area and is listed as rare in New Mexico and Arizona.

Leaves are hairy, flowers range from pink to purple, and the pods are curved and often purple speckled (look below the ruler for young pods and just to the left of the ruler for a more mature, speckled pod). Plants are from one-half to three inches tall.

Astragalus cottamii was first collected by Harrison in southern Utah and was named A. monumentalis by Rupert Barneby in 1953. Stanley Welsh named it A. cottamii in 1970. It is now considered a variety of A. monumentalis by Kartesz and Intermountain Flora. The plant is named for Utah botanist Walter Cottam. (More biographical information.)

Astragalus eastwoodiae
Fabaceae (Pea Family)

Semi-desert. Openings. Spring.
Canyons of the Ancients National Monument, March 17, 2005.

This is another early spring Astragalus; it grows in dense and large tufts of numerous arching leaflets, usually on reddish stems.

Beautifully symmetrical, delicately streaked flowers top the mass of leaves on leafless straight stems.

Where you find one mound of this plant, you will often find a dozen more within twenty feet.

Alice Eastwood was a Denver teacher, Colorado plant collector, and long-time Curator of the California Academy of Sciences Herbarium. (More biographical information.)