Pontederia subg. Eichhornia (Kunth) M.Pell. & C.N.Horn. A–B habit: A habit of P. heterosperma (Alexander) M.Pell. & C.N.Horn, showing the emerged petiolate leaves B habit of P. diversifolia (Vahl) M.Pell. & C.N.Horn, showing the floating petiolate leaves C–F inflorescence: C 2–3-flowered inflorescences of P. diversifolia, showing the flowers with a yellow nectar guide in the posterior perianth lobes D 1-flowered inflorescence of P. natans P.Beauv., showing the lack of a nectar guide E inflorescence of P. heterosperma, showing the lack of nectar guides in the posterior perianth lobes F morphological variation of inflorescences and perianth colour of P. azurea Sw G front view of a flower of P. azurea H front view of a flower of P. natans. A, B by O. Gaubert C by A.S. Castro D by P. Birnbaum E by H. Medeiros F by L.O.A. Teixeira G by M.O.O. Pellegrini and I by T.C. Buruwate.