Pontederia subg. Cabanisia (Klotzsch ex Schltdl.) 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

1. Pontederia subg. Cabanisia (Klotzsch ex Schltdl.) M.Pell. & C.N.Horn comb. et stat. nov. Fig. 5

Cabanisia Klotzsch ex Schltdl., Abh. Naturf. Ges. Halle 6: 176. 1862. Type species (designated here). Cabanisia caracasana Klotzsch ex Schltdl., nom. illeg. (≡ P. paniculata Spreng.).

Description.

Herbs perennial or annual, aquatic to amphibious, erect-emergent. Rhizome short and generally inconspicuous. Stems erect, spongy, branching at the base. Sessile leaves early deciduous. Petiolate leaves spirally-alternate, congested at the apex of the stem, emergent, ligule truncate, petioles not-inflated, blades cordate to broadly cordate, rarely elliptic to lanceolate or narrowly ovate. Main florescences (inflorescences) terminal, sessile or pedunculate; inflorescence leaf with an inflated leaf-sheath; basal bract flat; cincinni alternate or fascicle-like, 1-3-flowered, pedunculate, rarely sessile, internodes elongate, rarely contracted. Flowers sessile, chasmogamous, tristylous, zygomorphic, non-enantiostylous, perianth connate forming a tube, hypocrateriform, spirally-coiled at post-anthesis, non-deliquescent and tightly enclosing the developing fruit, lobes 3 superior and 3 inferior, rarely 5 superior and 1 inferior, the central superior lobe with a nectar guide, consisting of 2 yellowish-green to green spots, generally surrounded by a dark purple to bluish-purple, rarely white blur; stamens dimorphic, filaments free from each other, J-shaped, glandular-pubescent, anthers dorsifixed, rimose; ovary with 3 fertile locules, multi-ovulate, septal nectaries present, style glandular-pubescent, stigma capitate to trilobate. Capsules loculicidal, ellipsoid to oblongoid; anthocarp thickened, ridged. Seeds subglobose to broadly oblongoid, testa longitudinally winged.

Circumscription.

Pontederia subg. Cabanisia is composed by P. meyeri (A.G.Schulz) M.Pell. & C.N.Horn comb. nov., P. paniculata Spreng. and P. paradoxa Mart. All three species occur in moist environments or shallow waters, being similar in habit to well-known species of P. subg. Pontederia , such as P. cordata L. Nonetheless, both subgenera can be differentiated based on gynoecium, fruit and seed morphology.

Distribution.

Mainly Central-West and Northeastern Brazil (reaching Argentina and Paraguay), growing in temporary water bodies in the Caatinga, Cerrado and Chaco domains. However, two species have very peculiar disjunctions in their distributions, also occurring in north-western South America (Colombia, Ecuador, Guyana and Venezuela), Central America (Costa Rica, Guatemala and Nicaragua), Antilles (Jamaica) and North America (Mexico).

Figures

Figure 5. Pontederia subg. Cabanisia (Klotzsch ex Schltdl.) M. Pell. & C. N. Horn. A habit B-C inflorescence: B young inflorescence, showing the inflated leaf-sheath and flat basal bract with caudate apex C mature inflorescence showing the pedunculate cincinni with elongate internodes D detail of a cincinni, showing (from left to right) an immature floral bud, a pre-anthesis floral bud and a post-anthesis flower E front view of a flower F detail of an immature capsule, showing the ridged anthocarp. All photos of P. paniculata Spreng.; A by C. Willig & L. Nusbaumer, remaining photos by M. O. O. Pellegrini.