Cooperia pedunculata

Liliaceae (Lily family)


Rainlily grows from a black underground bulb up to 1.5 inches tall, conical when young and becoming flattened to round. The 0.5-inch-wide linear leaves become narrower toward the end and may be up to 14 inches long depending on rainfall and soil moisture. Each leaf ends with dry, desiccated material measuring from less than 0.25 inch to as much as several inches long. A flower stalk up to 8 inches high with a single white bloom up to 2 inches across appears a few days after a rain. The plant may or may not have leaves when the flower appears.


Rainlily is found in east, central and southwestern Texas. Depending upon the region, it may be found along streams, in valleys or on hillsides.

Toxic Agent

The toxic agent of rainlily has not been identified, but it is found only in the dead leaf tips of plants growing in a limited geographical area. Biological examinations of specimens throughout the range indicate that plants in and near DeWitt, Gonzales and Caldwell counties are highly photodynamic while those from other areas have little or no photoactivity. Photosensitivity occurs primarily in the fall, but also during late spring or summer, usually within 10 days after a rain. This suggests that some microbiological activity on the dead leaf material is responsible for the activity. Severe outbreaks of photosensitization occur when rain falls on a large amount of dead leaves.

Signs of Livestock Ingestion

Rainlily causes primary photosensitization, and poisoning results in loss of production but usually not death. The clinical signs are those of sunburn and include: Photophobia (animals try to stay in shade); Sunburn of light-colored skin; Crusting and cracking of light colored skin; Sloughing of skin.

This plant most often affects cattle in areas where the plants have high photoactivity. Severe outbreaks have included whitetailed deer. Deer and black cattle may become blind, and their eyes may turn cloudy and blue.

Management Strategies

Place affected animals in the shade and give them adequate feed and water. Give supplemental feed to calves nursing severely affected cows, as they are often not allowed access to painful udders. Most ranchers with large rainlily populations in DeWitt County have only black cattle, which prevents the majority of problems in most years.