Definition

Noun 1. A plant causing locoism: Any of several species of leguminous plants (plants belonging to the pea family, Fabaceae) native to western North America. Ingestion of these plants by livestock such as cattle, sheep, and horses causes a neurological disease known as locoism or "loco disease," characterized by erratic behavior, weight loss, and eventually death.

Examples

• The rancher was concerned when he found crazy weed growing in the south pasture.
• Crazy weed is one of the most problematic toxic plants for cattle in the region.
• The veterinarian identified the cause of the herd's strange behavior as poisoning from crazy weed.

Advanced Usage

• The term is used almost exclusively in an agricultural, veterinary, or botanical context concerning livestock poisoning and rangeland management.
• It is a common name that can refer to plants in genera such as (milkvetches) and (locoweeds), which contain the toxin swainsonine.

Variants and Related Words

• Locoweed: This is the more common and technically precise synonym for crazy weed. Both terms are used interchangeably.
• Locoism (noun): The disease or condition caused by eating locoweed/crazy weed.
• Locowed (adjective): Describing an animal affected by locoism.

Synonyms

• Locoweed
• Poison vetch (a general term for toxic species)

Notes on Meaning

The term crazy weed has a very specific meaning and is not used in general conversation. It does not refer to marijuana or any other psychoactive plant used by humans. Its entire definition is tied to its toxic effect on grazing animals.

Noun

1. any of several leguminous plants of western North America causing locoism in livestock