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