•
Senna acanthoclada (Griseb.) H.S.Irwin & Barneby (Argentina) •
Senna acatlanensis C.Rojas-Mart. & A.Delgado (Mexico) •
Senna acclinis (F.Muell.) Randell – rainforest cassia, brush senna (New South Wales) •
Senna aciphylla (Benth. ex A.Gray) Randell – sprawling senna, Australian senna (eastern Australia) •
Senna aculeata (Pohl ex Benth.) H.S.Irwin & Barneby (South America) •
Senna acunae (Borhidi) A.Barreto & Yakovlev (Cuba) •
Senna acuparata H.S.Irwin & Barneby (Ecuador, Peru) •
Senna acuruensis (Benth.) H.S.Irwin & Barneby (Brazil) •
Senna acutisepala (Benth.) H.S.Irwin & Barneby (Brazil) •
Senna affinis (Benth.) H.S.Irwin & Barneby (Bolivia, Brazil) •
Senna alata (L.) Roxb. – candlebush, Christmas candle (South America, Central America) •
Senna alexandrina Mill. – Alexandrian senna (North Africa, India, Pakistan) •
Senna andrieuxii (Benth.) H.S.Irwin & Barneby (Mexico) •
Senna angulata (Vogel) H.S.Irwin & Barneby (Brazil) •
Senna angustisiliqua (Lam.) H.S.Irwin & Barneby (Caribbean Islands) •
Senna ankaranensis Du Puy & R.Rabev. (Madagascar) •
Senna anthoxantha (Capuron) Du Puy (Madagascar) •
Senna aphylla (Cav.) H.S.Irwin & Barneby (Argentina) •
Senna apiculata (M.Martens & Galeotti) H.S.Irwin & Barneby (Mexico, Argentina) •
Senna appendiculata (Vogel) Wiersema (Brazil) •
Senna apsidoneura (H.S.Irwin & Barneby) H.S.Irwin & Barneby (Bolivia) •
Senna araucarietorum H.S.Irwin & Barneby (Brazil) •
Senna argentea (Kunth) H.S.Irwin & Barneby (Mexico) •
Senna arida (Rose) H.S.Irwin & Barneby (Mexico) •
Senna aristeguietae H.S.Irwin & Barneby (Brazil, Venezuela) •
Senna armata (S.Watson) H.S.Irwin & Barneby (Arizona, California, Mexico Northwest, Nevada) •
Senna arnottiana (Gillies) H.S.Irwin & Barneby (Argentina, Chile) •
Senna artemisioides (Gaudich. ex DC.) Randell – silver cassia (Australia) •
Senna atomaria (L.) H.S.Irwin & Barneby (Mexico to Venezuela, Caribbean) •
Senna aurantia (Ruiz & Pav. ex G.Don) H.S.Irwin & Barneby (Peru) •
Senna auriculata (L.) Roxb. – avaram, Matara-tea, tanner's cassia (Indian subcontinent, Myanmar) •
Senna aversiflora (Herb.) H.S.Irwin & Barneby (Brazil) •
Senna aymara H.S.Irwin & Barneby (Bolivia) ==B==