Senna Species, Arsenic Bean, Coffeeweed, Coffee Senna, Mogdad Coffee, Septicweed, Stinking Weed

Senna occidentalis

Family: Fabaceae (fab-AY-see-ee) (Info)
Genus: Senna (SEN-nuh) (Info)
Species: occidentalis (ok-sih-den-TAY-liss) (Info)
Synonym:Cassia caroliniana





Water Requirements:

Unknown - Tell us

Sun Exposure:

Full Sun

Sun to Partial Shade


Unknown - Tell us

Foliage Color:

Unknown - Tell us


36-48 in. (90-120 cm)

4-6 ft. (1.2-1.8 m)


Unknown - Tell us


Not Applicable

Where to Grow:

Unknown - Tell us


All parts of plant are poisonous if ingested

Bloom Color:

Gold (yellow-orange)

Bright Yellow

Bloom Characteristics:

Unknown - Tell us

Bloom Size:

Unknown - Tell us

Bloom Time:

Late Spring/Early Summer

Mid Summer

Other details:

May be a noxious weed or invasive

Soil pH requirements:

5.1 to 5.5 (strongly acidic)

5.6 to 6.0 (acidic)

6.1 to 6.5 (mildly acidic)

Patent Information:


Propagation Methods:

Direct sow as soon as the ground can be worked

Seed Collecting:

Allow pods to dry on plant; break open to collect seeds

Allow seedheads to dry on plants; remove and collect seeds

Gardeners' Notes:


On Oct 12, 2021, Korwynn from Roanoke, VA wrote:

All varieties of coffee weed Iíve seen are deadly. It takes 3-5 plants with 3-5 pods to kill an adult bull. Autopsy showed massive internal bleeding. They are only eaten after the plant dies, because alive they are pungent. The awful smell attracts wasps who use it to protect their nests. Seeds can lie dormant for years. My advice is to destroy this plant as soon as you discover it. The herd tends to learn not to eat it after 4 deaths.


On Nov 1, 2017, JeffreyCaldwell from Waldon, CA wrote:

Looking this plant up since I just discovered that it serves as caterpillar forage for the Cloudless Sulphur butterfly. Seems particularly popular with it on the Caribbean island of Martinique, according to the Catalogue of the Lepidoptera of the French Antilles:


On Aug 5, 2007, btc129psu from Houston, TX (Zone 9a) wrote:

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 ... read more


On Aug 5, 2004, Farmerdill from Augusta, GA (Zone 8a) wrote:

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 n... read more