Pontederia L. subg. Pontederia

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

5. Pontederia L. subg. Pontederia Fig. 9

Michelia Adans., Fam. Pl. 2: 201. 1763, nom. illeg. Type species (designated here). Pontederia cordata L.

Narukila Adans., Fam. Pl. 2: 54. 1763, nom. illeg. Type species (designated here). Narukila cordata (L.) Nieuwl. (≡ P. cordata L.).

Pontederaea Kuntze, Revis. Gen. Pl. 2: 718. 1891, orth. var.

Pontederas Hoffmanns., Verz. Pfl.: 137. 1824, orth. var.

Reussia Endl., Gen. Pl.: 139. 1836. Type species (designated by Lowden 1973). Reussia triflora Endl. ex Seub. [≡ P. triflora (Endl. ex Seub.) G.Agostini et al.].

Unisema Raf. Med. Repos. 5: 352. 1808, nom. illeg. Type species. Unisema obtusifolia (Raf.) Raf. (≡ P. cordata L.).

Umsema Raf. Med. Repos. 5: 352 1808, orth. var.

Unisemma D.A.Godron, in Orbigny CVD, Dict. Univ. Hist. Nat.: 761. 1848, orth. var.

Description.

Herbs perennial or annual, aquatic to amphibious, erect-emergent or procumbent-emergent. Rhizome short and generally inconspicuous. Stems erect or trailing, spongy, unbranched to branching only at the base to branched. Sessile leaves early deciduous. Petiolate leaves distichously-alternate, evenly distributed along the stem or 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 without an inflated leaf-sheath; basal bract flat; cincinni alternate, 1-3-flowered, sessile to shortly-pedunculate, internodes contracted. Flowers sessile, tristylous, zygomorphic, non-enantiostylous, perianth connate forming a tube, infundibuliform, revolute at post-anthesis, non-deliquescent and loosely 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, coiling or post-anthesis; stamens dimorphic, filaments free from each other, J-shaped, glandular-pubescent, anthers dorsifixed, rimose; ovary with 1 fertile locule, 1-ovulate, septal nectaries present, style glandular-pubescent or glabrous, stigma truncate or capitate or trilobate. Achene ovoid or pyriform; anthocarp hardened, ridged, ridges sinuate, toothed or echinate. Seeds curved narrowly ovoid or ovoid, testa smooth.

Circumscription.

Pontederia subg. Pontederia is circumscribed by us to comprise eight species. Our concept of P. subg. Pontederia is equivalent to the concept of Pontederia adopted by Lowden (1973). Nonetheless, we accept P. triflora as distinct from P. subovata and increase the number of species in the P. cordata complex by the re-establishment of P. ovalis . The members of this subgenus are peculiar within Pontederia s.l. due to their spike-like main florescences, ovaries 1-locular by abortion, fertile locule 1-ovulate, pendulous placentation, fruit an achene, hardened and ornate anthocarps and smooth seeds.

Distribution.

Exclusively Neotropical.

Figures

Figure 9. Pontederia L. subg. Pontederia. A-C habit: A dense population of P. parviflora Alexander B population of P. ovalis Mart. ex Schult. & Schult. f. C habit of P. rotundifolia L. f. D-E petiolate leaves: D blade of P. rotundifolia E blade of P. parviflora F-H inflorescences: F inflorescence of P. cordata L., showing flowers with two yellow nectar guides in the posterior perianth lobes G inflorescence of P. parviflora, showing flowers with a sole yellow nectar guide in the posterior perianth lobes H inflorescence of P. rotudifolia, showing a lilac-flowered form I oblique view of a flower of P. ovalis J-K fruits: J detail of the apex of the infructescence of P. ovalis, showing the anthocarp with sinuate ridges K detail of an achene of P. cordata, showing the toothed ridges. A by C. Willig & L. Nusbaumer B, I, J by M. O. O. Pellegrini C by L. O. A. Teixeira, D, H by R. Aguilar E by M. R. Engels F by Ashitaka-f Studio G by M. V. Lameiras and K by A. Haines.