WordNet (r) 3.0 (2006):

true senna
    n 1: erect shrub having racemes of tawny yellow flowers; the
         dried leaves are used medicinally as a cathartic; sometimes
         placed in genus Cassia [syn: Alexandria senna,
         Alexandrian senna, true senna, tinnevelly senna,
         Indian senna, Senna alexandrina, Cassia acutifolia,
         Cassia augustifolia]