locoweed

locoweed or crazyweed [Span. loco=crazy], any of several American species of the genera Astragalus and Oxytropus, north-temperate leguminous plants of the family Leguminosae (pulse family), that, when eaten by horses, cattle, or sheep, cause a nervous disorder called loco disease. The locoweeds, perennials native to the West and Southwest, have pealike flowers and pinnately compound leaves. Not all species of these genera have been found poisonous. An Old World plant related to the Astragalus locoweeds is the source of gum tragacanth. Locoweed is classified in the division Magnoliophyta, class Magnoliopsida, order Rosales, family Leguminosae.

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locoweed

Any of several species of poisonous plants of the genera Astragalus and Oxytropis, in the pea family (see legume), native to the prairies of north-central and western North America. These low-growing plants (up to 1.5 ft [45 cm] high) have variably hairy, fernlike leaves and spikes of pealike flowers. They pose a danger to grazing animals because they contain a toxin that affects muscle control, producing frenzied behaviour, impaired vision, and sometimes death. Because they taste bad, livestock usually eat them only when other forage is scarce. Decaying locoweeds release toxins into the soil that are sometimes absorbed by otherwise harmless forage crops.