Total evidence phylogeny of Pontederiaceae (Commelinales) sheds light on the necessity of its recircumscription and synopsis of Pontederia L. Pellegrini, Marco O. O. Horn, Charles N. Almeida, Rafael F. PhytoKeys 2018 108 25 83 FDB65AB9-8F5A-5002-91F2-FEC3C10022B8 L., Sp. Pl. 1: 288. 1753. Liliopsida Pontederiaceae Pontederia CoL Plantae Pontederia Commelinales 0 25 Tracheophyta genus  Type species (designated by Lowden 1973).   Pontederia cordataL.  Description.  Herbsperennial or annual, aquatic to amphibious, erect-emergent, procumbent-emergent or free-floating. Rootsthin, fibrous or spongy. Rhizomeshort and generally inconspicuous. Stemstrailing to erect, delicate to spongy, branching at the base, rarely branching at the upper half, rooting at the basal nodes or along the whole stem; internodes reduced to elongate, producing stolons or not.  Sessile leavesdistichously-alternate, congested at the apex of the stem, submerged, deciduous or persistent in mature plants, blades linear to linear-obovate, membranous, rarely chartaceous.  Petiolate leavesdistichously or spirally-alternate, congested at the apex of the stem or evenly distributed along the stem, floating or emergent, ligule truncate or with a flabellate projection; petioles conspicuous, rarely indistinct, inflated or not; blades elliptic to lanceolate or ovate to cordate to reniform or obovate to rounded, chartaceous to coriaceous. Synflorescencecomposed by a solitary main florescence subtended by a vegetative, petiolate leaf. Main florescences (inflorescences)axillary or apparently terminal, consisting of a pedunculate, many-branched thyrse, rarely a reduced thyrse; inflorescence leaf with or without an inflated leaf-sheath; basal bract flat or tubular; cincinnus'bract absent; cincinni (1 -3-)4 - many per thyrse, alternate or fascicle-like, 1 - many-flowered, sessile or pedunculate, internodes contracted, rarely elongate; bracteoles absent, rarely present. Flowersbisexual, sessile or pedicellate, chasmogamous, pseudo-homostylous or tristylous, enantiostylous, zygomorphic, perianth connate usually forming a tube (hypanthium), rarely only basally fused, campanulate or infundibuliform or hypocrateriform, white to light pink to pink to mauve to pale lilac to lilac to bluish-lilac to purple, lobes 6 (3 outer and 3 inner), elliptic to oblong to obovate, 3 superior and 3 inferior, rarely 5 superior and 1 inferior, the central superior lobe generally with a nectar guide, consisting of 1-2 yellow to green spots, generally surrounded by a dark purple to bluish-purple, rarely white blur, spirally-coiling or revolute at post-anthesis, deliquescent or not; stamens 6, epipetalous, dimorphic (the superior 3 shorter than the inferior 3) or unequal (1 inferior longer with a differently coloured anther), filaments J-shaped or recurved-decurved, terete, glabrous to glandular-pubescent, anthers dorsifixed, sometimes basifixed, rimose or poricidal, oblong to elliptic or sagittate; ovary ellipsoid to oblongoid, glabrous, locules 3, (1-)3 fertile, (1-)multi-ovulate, placentation axial or pendulous, septal nectaries generally present, rarely absent, style J-shaped, glabrous to glandular-pubescent, stigma capitate to trilobate, rarely trifid. Fruita capsule with loculicidal or irregular dehiscence, rarely an achene, ellipsoid to oblongoid to subglobose or ovoid, rarely pyriform, light to medium brown, apiculate due to persistent style base; anthocarp thin or hardened, smooth or ridged, ridges ornamented or not. Seedsoblongoid or ellipsoid or subglobose to broadly oblongoid or ovoid or curved narrowly ovoid, brown to light-brown, testa longitudinally conspicuously to inconspicuously winged, rarely smooth, when present, wings membranous and testa also transversally striated between each wing; funiculi generally persistent, hilum punctate; embryotega dorsal, not prominently apiculate, darker than the rest of the seed.  Distribution and habitat.   Pontederiacurrently comprises 26 mainly Neotropical species. Almost all Paleotropical species belong to P. subg. Monochoria(C.Presl) M.Pell. & C.N.Horn comb. et stat. nov.; except for  P. natansP.Beauv., which is restricted to Africa and is a member of P. subg. Eichhornia(Kunth) M.Pell. & C.N.Horn comb. et stat. nov.Species in  Pontederiacan range from paludal to free-floating plants, thus occurring in a wide range of water bodies, from perennial to temporary, but most commonly in slow or stagnated water.  Generic circumscription and infrageneric classification. The circumscription adopted by us is almost equivalent to the original one proposed by Linnaeus (1753). It differs only by the exclusion of  P. ovataL., which is currently placed in Marantaceaeas a synonym for  Phrynium pubinerveBlume ( Horn and Haynes 1987; eMonocot 2010). Thus, no amendments are necessary for the herein adopted circumscription. We propose the subdivision of  Pontederiain five monophyletic subgenera, based on the previously published molecular and morphological phylogenies ( Eckenwalder and Barrett 1986; Graham and Barrett 1995; Kohn et al. 1996; Barrett and Graham 1997; Graham et al. 1998, 2002; Ness et al. 2011), added to the new morphological and molecular analyses presented by us and data gathered by us while working on the family. Despite being monophyletic, these subgenera are not easily morphologically differentiated, since many of the characters supporting each clade are not always easy to observe, especially in dried specimens. Thus, it is our opinion that a broader sense of  Pontederiashould be accepted, instead of elevating each  Eichhornialineage (i.e. the herein proposed subgenera) to the generic rank.