PlantFiles: Coffee Weed, Coffee Senna, Stinking Weed, Stinking Wood
Senna occidentalis

Coffee Senna is not as toxic as many have been led to believe. The seeds are the only part of the plant which are dangerously toxic to humans and animals in small quantities. The rest of the plant is only dangerous to humans in very high doses. The plant has been used in Central America and currently in many other subtropical regions of the world for generations as a medicinal herb. Like many pharmaceuticals, the compounds in the Senna genius can be dangerous if administered improperly but in more moderate doses can provide numerous medical benefits.

On a recent trip to Senegal I observed numerous families cultivating this plant for its leaves. The families all told me they made tea from the leaves for stomach problems. One women gathering a particularly large load leaves also told me she intended to use them for joint pain. Similar uses are reported from around the world and coffee senna has indeed been proven as a diuretic and liver detoxifier. Antibacterial, antiviral, antifungal and numerous other properties have also been demonstrated.

While this does not mean the plant is safe in the sense our average garden herbs are safe, it does mean that coffee senna should recieve a little more respect from us. This should be a healthy and informed respect, however, and anyone growing the plant should be aware that it is a proven danger to livestock (principaly the seed pods) and potentialy to crops. The plant can be controlled, however, via careful management of its planting and trimming of the seeds. The plant produces beatiful flowers which turn into interesting spikies of upright curved seed pods. These pods dry on the plant before splitting open and dropping the seeds. For control the pods can be cut and safely discarded anytime betweent the point the flower dies to the time the pod begins to turn brown.

Besides being considered a noxious weed by some it may also be considered invasive in some areas. While the plant is indeed an interesting specimen, the utmost responsibility should be taken in its management to prevent any further harm to humans, the environment, and the reputation of this plant.

As a side note, I believe the first image posted by Farmerdill may not be Senna occidentalis. S. occidentalis as far as I know always has pointed leaves. I am not an expert on this genus but it looks like a different senna species, maybe obtusifolia. Nonetheless many senna species produce the same or similar chemicals and toxins and Farmerdill's description is probably applicable to both species.

This is a toxic weed. It is not a major threat to row crops as it it easily controlled by cultivation. It is hazardous to grazing animals especially horses. The seeds are particularly hazardous in that they contaminate machine harvested grain and soybeans. The plant biology department of UGA says the following "All parts of the plant are considered toxic, fresh or dry, especially the seeds which can contaminate feed grains.
The toxic compound found in coffee weed is believed to be an anthraquinone. Clinical signs include decreased muscle tone, muscular weakness, slow or odd gait, anorexia, and diarrhea. In cattle many researchers have reported reddish urine and labored breathing and increased heart rate in the terminal stages. In cattle when the animal becomes prostrate they do not usually recover. Coffee weed has been shown to be toxic to goats, sheep, rabbits, chickens, and cattle. "