tropical shrub, 1540s (by 1570s in reference to the drug made from dried leaflets of different species), from Modern Latin senna, from Arabic al-senā. Earlier was sene (c. 1400), from French.
This is planted in Syria and AEgypt, also in Italie, in Prouence of Fraunce, in Languedocke. It hardly groweth in high and lowe Germanie neither in England .... The best is brought from Alexandria and out of AEgypt. The Arabians were the first that found it out. [John Gerarde, "The Herball, or Generall Historie of Plantes," 1597]