Oxytropis sericea sericea

White Locoweed - Oxytropis sericea sericea
East of Hillsboro, New Mexico
April 9, 2014

On walks on the east side of the Black Range it is easy to encounter two species of Oxytropis in April.  Oxytropis sericea sericea, or White Locoweed (also - White Point-Vetch, Whitepoint Crazyweed, and Silky Crazyweed) is a white flowering legume.  Oxytropis pinetorum is a scientific synonym for this species.

It is a common cause of livestock poisoning, causing locoism which is a neurological condition (however, see below).  The active agent in the plant is an alkaloid named swainsonine.  As with many alkaloids, in can be addictive.  Ingestion causes a full range of terrible symptoms which can end in death, but generally only after significant rates of consumption over a period of one to three months.  The flowers, which cattle seem to prefer, have a higher concentration of swainsonine than do the leaves.  These traits have been problematic for some cattlemen.

The range of the species in the lower 48 of the United States is shown on the BONAP map to the right.  The light green color indicates that the species is native to and not rare within the county indicated.

The other species of Oxytropis found at this time of year near Hillsboro is Oxytropis lambertii (Purple Locoweed, Woolly Locoweed, or Lambert Crazyweed). 

The specimen shown below was collected by Allen on the Yellowstone Expedition of 1873.  It was originally classified as Oxytropis lambertii.

© Robert Barnes 2018-2023