Senna occidentalis (Coffee Senna)

Senna occidentalsSenna occidentalis (Coffee Senna) Aka Septicweed, Hedionda, Coffeeweed, Mogdad coffee, Negro-coffee, Senna coffee, Stephanie coffee, Stinkingweed or Styptic weed, is a pantropical species native to the tropical and subtropical regions of the Americas, and naturalized elsewhere. It formerly belonged to the Cassia genus, now it’s Senna.Senna occidentalis It belongs to the Fabaceae family. This was shot handheld at f/16, ISO 200, which gave me a 1/60th sec. shutter speed and good enough depth of field for the stamens. I found it at an abandoned lot in San  Juan, P.R. before I left in December.

Senna occidentalis (Septicweed)The popular name “septicweed” refers a foul odour when damaged. Formerly placed with the Cassia genus, now it’s with Senna. “Senna” derives from Arabic and means “bright light.” Occidentalis is Latin, meaning ‘of the west’, indicating that the plant is a native of the western hemisphere, principally the Americas. The genus Senna has had a diverse  taxonomic history. What is now known as Senna was included by Linnaeus in his concept of Cassia in Species Plantarum in 1753. Others in this group are “Chamaecrista and Cassia”.

Senna occidentalis (Septicweed)Phylogenetic analyses of DNA have shown that Chamaecrista, Cassia, and Senna are all monophyletic, but the relationships between these three genera is not clear.  They are therefore shown in phylogenetic trees as a tritomy.

SennaIn Jamaica the seeds are roasted, brewed and served as tea to treat various conditions. They are also called  “coffee Senna seeds” and “Mogdad coffee.” “Mogdad” is the name which originated in Senegal, western Africa. The seeds can be roasted and used as a substitute or adulterant for coffee. However, there is no caffeine in Mogdad coffee. 

Senna occidentalisHere you can see the alternate, compound, paripinnate leaflets. The flowers have 5 petals and 10 stamens, unequal in size, 7 perfect and 3 reduced to staminodes. Note the leaves are NOT bipinnate, which can easily make it seem like  Chamaecrista fasciculata, the partridge pea plant, which is a true native to the U.S..

occidentalisCassia occidentalis L [now Senna occidentals], Botanical Register, vol. 1: t. 83 (1815) [S. Edwards] drawing: S. Edwards



27 thoughts on “Senna occidentalis (Coffee Senna)

    • Isabel, puede ser que la vaina estuviese un poco verde, y que por eso las semillas se veían amarillentas, aunque ya estaba la vaina de color marrón. Como siempre, gracias por visitar.


  1. One of my favorite Texas natives is Lindheimer’s senna (Senna lindheimeriana) I notice that they indicate Cassia lindheimeriana as a synonym. When I was traveling this fall, I came across partridge pea in both Arkansas and Kansas, and I’ve found it on our prairies here, too.

    When I first found the senna, I visited a museum that same day, and saw Lindheimer’s own herbarium sheet for the plant. It really was a thrill — especially to see the notes in his own hand.

    Liked by 1 person

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