A phytochemical study of the flowers of ARNICA CHAMISSONIS Less. subsp. FOLIOSA (Nutt.) Maguire (Asteraceae) has resulted in the identification of a further 23 helenanolides. Six of them, 2alpha-hydroxy-6- O-angelicoyl-2,3-dihydrohelenalin ( 3B), 2alpha-hydroxy-6- O-senecioyl-2, 3-dihydrohelenalin (