LOCO

"It's kind of odd about women," he went on, "and the place they're supposed to occupy in botany. If was asked to classify them I'd say they was a human loco weed" The Lonesome Road, ~ O. Henry

There are many species of Astragalus, and some of them are very hard to differentiate. A common one on the Wasatch foothills is Astragalus utahensis, also called the Pink Lady Slipper. Many of these are addictive and poisonous to livestock, causing an incurable insanity. They are called "loco weeds", from a Spanish word meaning "crazy".