Senna occidentalis

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Senna occidentalisWeed
Family: Fabaceae
Genus: Senna
Common names: Coffee Senna; Arsenic Bush
ALA reference

At our working bee on the 7th April we found a couple of unidentified plants with bright yellow flowers. In keeping with our standard practice we didn’t remove them till they had been identified in case they turned out to be natives. Thanks to my sister they have been identified as Senna occidentalis. This species is a native of America but is now a pantropic weed. It grows from about 1 metre to 2 metres tall and is usually an annual or short lived perennial. It can be easily identified by the following features:

  • 3 to 7 pairs of pointed leaflets on a leaf that is up to 18 cm long
  • the leaves emit an unpleasant foetid smell when handled
  • an absence of glands between the leaflets and a single mounded gland at the base of the leaf

(April 2013)