Canna 'Orange Tiger' is a small Italian Group cultivar, with variegated leaves and orange flowers.
Canna 'Orange Vif' is a medium-sized Crozy Group cultivar, with green leaves and orange flowers.
Canna 'Orange Zest' is a small Crozy Group cultivar, with dark leaves and orange flowers.
Orangeade requires research.
Orangeman requires research.
Orchid is a synonym of City of Portland.
Canna 'Oriental' is a tall Crozy Group cultivar, with green leaves and yellow flowers.
orientalis Bouché is a synonym of indica var. indica.
orientalis f. flava Roscoe is a synonym of indica var. flava (Roscoe, Baker) Nb. Tanaka.
orientalis Roscoe requires research.
Oriflamme requires research.
Oriole requires research.
Oscar Dannecker requires research.
Canna 'Osric' is a small Premier Group cultivar, with green leaves and pink flowers.
Othello requires research.
Canna 'Ottawa' is a medium-sized Crozy Group cultivar, with green leaves and pink flowers.
ottonis (Bouché) Kraenzl. is a synonym of paniculata.
Out of Africa is a synonym of Red King Humbert.
P. Marquant requires research.
P.J. Berkman is a synonym of P.J. Berkmans.