Line drawing of Heteranthera pumila M.Pell. & C.N.Horn. A Habit B Detail of the apex of the stem, showing a petiolate leaf, the ligule and a pre-anthesis 2-flowered inflorescence C Glandular hair from the inflorescence, perianth tube and lobes D Dissected perianth lobes, showing the 5+1 arrangement E Lateral stamen. F Uniseriate hair from the lateral stamen G Central stamen H Eglandular hair from the central stamen I Gynoecium, showing the stigma J Eglandular hair from the style K Detail of the inconspicuously winged seed, showing the persistent funiculus with raphid crystals. Illustration by M.O.O. Pellegrini, based on the holotype.