Astragalus agnicidus

Common Names:
Humboldt milkvetch
Growth Habit:
CPC Number:
Profile Contributors:
Edward Guerrant, Ph.D.
Fully Sponsored

Reference Links

ITIS - Tropicos - USDA Plants - Fish & WildLife

Participating Institutions

The following Participating Institutions are custodians for this species in the CPC National Collection:
Rae Selling Berry Seed Bank & Plant Conservation Programs
Rancho Santa Ana Botanic Garden

The conservation of Astragalus agnicidus is fully sponsored.
Edward Guerrant, Ph.D. contributed to this Plant Profile.


Throughout history, humans have systematically eradicated plants and animals that seem to pose a threat to their livestock or crops. Bears, wolves, coyotes, and even condors have all been victims of ranchers' guns and traps. Astragalus agnicidus has fallen victim to the rancher's shovel and herbicide use. Fortunately, recent changes in scientific thought and public opinion have helped people to see these species not as "threats" but as integral parts of native ecosystems, and therefore, worthy of our protection.

For over seventy years, the only known site containing Astragalus agnicidus was a privately owned 8-acre ranch in Humboldt County, CA. In the 1930s and 40s, the owners logged and cleared portions of their land in order to raise sheep. When several sheep were found dead, the concerned owners enlisted the help of a local County Agriculture Extension employee. He identified the "culprit" and encouraged them to eradicate the plant (although many members of the genus Astragalus are toxic to livestock, some now believe that in this instance, the real killer may have been a lupine). But the damage was done, both literally and figuratively. When the species was formally named in 1957 it was given the specific epithet of agnicidus, which means lamb killer (the lamb killing locoweed is a much less appealing common name than Humboldt milkvetch). The landowners appeared to have been successful in their quest to eradicate this plant, as in 1954, only one plant was found. No more were found and it was presumed extinct until it was re-discovered. In 1985, bulldozers were used to clear a fallen tree that was considered a fire hazard. Two years later, 25 Astragalus agnicidus plants were found in the area and another 75 were found in a nearby clearing. The canopy opening created by the fallen tree coupled with the soil disturbance caused by the heavy equipment that removed the tree created suitable conditions for the seeds, which had lain dormant in the soil for at least 30 years, to germinate (see the research and ecology sections for more).

Like many others who now see the value in conserving all aspects of native ecosystems, the same family that once worked to eradicate the plant is now enthusiastic about conserving it. The population is currently protected by a voluntary agreement between the landowner and The Nature Conservancy and the land is being managed for the species' continued survival. Astragalus agnicidus was removed from the Federal Endangered and Threatened Candidate list in 1996 (U.S. Fish and Wildlife Service, 1996) largely because of this protection agreement. In 1999 and 2000, two new sites containing A. agnicidus were discovered on timberland that had recently been logged.

It appears that apparently extinct species can arise, phoenix-like, out of the ashes of oblivion from naturally occurring as well as artificial seed banks.

Distribution & Occurrence


Conservation, Ecology & Research