Brazos County Herbarium

Brazos County Horticulture Extension

Lindheimer Senna

Senna lindheimeriana

Fabaceae (Legume family)

Description

Lindheimer senna is an erect, perennial, foul-smelling legume with one to several velvety stems arising from a deep, woody root. Its compound leaves are hairy, spirally arranged and have five to eight pairs of oblong leaflets. The flowers, which have five yellow petals, are borne in upper leaf axils and are in spikes about as long as the leaves.

Habitat

This senna is found primarily in the Edwards Plateau, west through the Trans-Pecos and to Arizona and south into Mexico. It is common in shallow limestone soil, on hillsides and rocky ravines.

Toxic Agent

The compounds responsible for the toxicity of Senna are unknown. Lindheimer senna is very unpalatable and is consumed only in unusual circumstances. The plant has not been proven toxic by experimental feeding trials, but has been implicated in bovine deaths. In one case, cows from the Midwest were transported to the Hill Country and turned out in a small pasture containing a large amount of lindheimer senna. The hungry animals consumed a large amount of the plant, then displayed a clinical syndrome typical of coffee senna poisoning. Examined after death, they also had similar muscle lesions.

Signs of Livestock Ingestion

The clinical signs are those of animals with severe muscle damage and gastrointestinal disturbance and include: Diarrhea; Weakness; "Alert downers"-not depressed, will eat, but unable to rise; Dark urine; Death; Few animals that go down will recover.

Management Strategies

Poisoning can be prevented by not forcing cattle to consume these plants. Always fill animals new to an area with good forage before placing them in pastures where toxic plants are growing.

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