Southwest Colorado Wildflowers, Astragalus 2

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.

Astragalus lonchocarpus
Fabaceae (Pea Family)

Canyons, foothills. Shrublands, openings. Spring.
Canyons of the Ancients National Monument, April 19, 2007.

Clusters of pale yellow to cream tubes dangle from several feet of new spring growth. Astragalus lonchocarpus is eye-catching because of its mass of bright green foliage and numerous stems of numerous flowers. Leaves are sparse and slender. Note that the flower stems on the left of the plant have all been snipped off by browsing deer.

"Lonchocarpus" is Greek for "spear-shaped fruit".

Augustus Fendler collected the first specimen of this plant in 1847 near Santa Fe and John Torrey named and described it in 1849.

Astragalus lonchocarpus
Fabaceae (Pea Family)

Canyons, foothills. Shrublands, openings. Spring.
Canyons of the Ancients National Monument, April 19, 2007.

Astragalus praelongus (Stinking Milkvetch)
Fabaceae (Pea Family)

Semi-desert. Shrublands, openings. Spring.
BLM lands near the San Juan River, Utah, April 6, 2005.

Astragalus praelongus has long, tubular, light yellow flowers in thick dangling clusters. Last year's seed pods, curled, sharp-tipped, and split open project in all directions. Stems are tall and light green and leaflets are numerous. The plant often grows on Selenium rich soils and picks up the characteristic Selenium fetid odor, thus the common name, Stinking Milkvetch. Beware! Touching this plant releases a really unpleasant Selenium stink. (See the very similar stinking Astragalus pattersonii.)

"Prae, longus", the Latin, "before, long" perhaps refers to the crowded young flowers soon becoming spaced out as the flower stem elongates.

Astragalus praelongus (Stinking Milkvetch)
Fabaceae (Pea Family)

Semi-desert. Shrublands, openings. Spring.
BLM lands near the San Juan River, Utah, April 6, 2005.

Astragalus praelongus (Stinking Milkvetch)
Fabaceae (Pea Family)

Semi-desert. Shrublands, openings. Spring.
Bisti/De-Na-Zin Wilderness Area, New Mexico, March 27, 2006.

Thick stems and large, dried seed pods make Astragalus praelongus fairly easy to identify long after flowering time.