Pontederia subg. Monochoria (C.Presl) M.Pell. & C.N.Horn, 2018

Pellegrini, Marco O. O., Horn, Charles N. & Almeida, Rafael F., 2018, Total evidence phylogeny of Pontederiaceae (Commelinales) sheds light on the necessity of its recircumscription and synopsis of Pontederia L., PhytoKeys 108, pp. 25-83 : 25

2. Pontederia subg. Monochoria (C.Presl) M.Pell. & C.N.Horn comb. et stat. nov. Fig. 6

Monochoria C.Presl, Reliq. Haenk. 1(2): 127. 1827. Type species. Monochoria hastifolia C.Presl., nom. illeg. (≡ P. hastata L.).

Calcarunia Raf., Med. Fl. 2: 106. 1830. Type species. Calcarunia hastata (L.) Raf., nom. inval. (≡ P. hastata L.).

Carigola Raf., Fl. Tellur. 2: 10. 1837. Type species. Carigola hastata (L.) Raf. (≡ P. hastata L.).

Gomphima Raf., Fl. Tellur. 2: 10. 1837. Type species. Gomphima vaginalis (Burm.f.) Raf. (≡ P. vaginalis Burm.f.).

Kadakia Raf. Fl. Tellur. 2: 9. 1837. Type species. Kadakia dilatata (Buch.-Ham.) Raf. (= P. hastata L.). Syn. nov.

Limnostachys F.Muell., Fragm. 1: 24. 1858. Type species. Limnostachys cyanea F.Muell. [≡ P. cyanea (F.Muell.) M.Pell. & C.N.Horn].

Description.

Herbs perennial or annual, aquatic to amphibious, erect-emergent or procumbent-emergent. Rhizome short to elongated. Stems erect, spongy, branching at the base. Sessile leaves early deciduous. Petiolate leaves distichously to spirally-alternate, congested at the apex of the stem, sometimes evenly distributed along the stem, floating to emergent, ligule truncate, petioles not-inflated, blades cordate to broadly cordate, rarely elliptic to narrowly ovate. Main florescences (inflorescences) terminal, sessile or pedunculate; inflorescence leaf with an inflated leaf-sheath; basal bract tubular, apex caudate, sometimes acute to acuminate, rarely leaf-like; cincinni alternate or fascicle-like, 1-3-flowered, sessile or pedunculate, internodes elongate, rarely contracted. Flowers pedicellate, chasmogamous, monostylous, actinomorphic or zygomorphic, enantiostylous, perianth connate only at base, campanulate, spirally-coiled at post-anthesis, non-deliquescent and tightly enclosing the developing fruit, lobes 3 superior and 3 inferior, the central superior lobe lacking a nectar guide; stamens unequal, filaments connate forming a petalo-staminal tube, J-shaped or recurved-decurved, glabrous, anthers basifixed, poricidal, dehiscent through two apical pores; ovary with 3 fertile locules, multi-ovulate, septal nectaries absent, style glabrous, stigma capitulate to capitate or trilobate to trifid. Capsules loculicidal, ellipsoid to oblongoid to subglobose; anthocarp thickened, ridged. Seeds cylindrical or ellipsoid to narrowly oblongoid to broadly oblongoid to subglobose or ovoid, testa longitudinally winged.

Circumscription.

Pontederia subg. Monochoria is composed of ten exclusively Paleotropical species. All species occur in permanently moist environments or shallow waters, growing either as erect or procumbent-emergent, resembling in habit smaller members of P. subg. Pontederia and even some species of Heteranthera . The members of this subgenus are quite unique within Pontederia s.l. due to their pedicellate flowers, perianth only basally connate, unequal stamens, basifixed and poricidal anthers and due to the secondary loss of the septal nectaries.

Distribution.

Exclusively Paleotropical ( Cook 1989), with two species native to Africa ( Verdcourt 1961), four to Australia (two endemic, Aston 1985) and six to Asia ( Wang et al. 2004).

Figures

Figure 6. Pontederia subg. Monochoria (C. Presl) M. Pell. & C. N. Horn. A-B habit: A paludal habit of P. australasica (Ridl.) M. Pell. & C. N. Horn B paludal habit of P. cyanea (F. Muell.) M. Pell. & C. N. Horn C ligule of P. vaginalis Burm. f., showing the truncate apex D-E petiolate leaf-blades: D blade of P. cyanea, showing the lack of a posterior division E blade of P. vaginalis, showing the presence of a posterior division F-G inflorescences: F inflorescence of P. australasica, showing the developed main axis G inflorescence of P. plantaginea Roxb., showing the contracted main axis H front view of a flower of P. korsakowii (Regel & Maack) M. Pell. & C. N. Horn I-J inflorescences at post-anthesis: I erect inflorescence of P. hastata L. bearing flowers at post-anthesis J infructescence of P. hastata, showing the deflexed posture and the elongated pedicels K sections of immature capsules of P. vaginalis, showing developing seeds. A, F by M. Barritt B by R. Cumming C, E, K by P. B. Pelser & J. F. Barcelona D by A. & S. Pearson G by D. Valke H by Ashitaka-f Studio and I & J by Cerlin Ng.