Aponogeton dassanayakei Manawaduge et al. (2016a: 251)

Manawaduge, Chapa G. & Yakandawala, Deepthi, 2018, Morphometrics and taxonomic update to the Sri Lankan Aponogetonaceae, Phytotaxa 365 (3), pp. 201-224 : 213

1. Aponogeton dassanayakei Manawaduge et al. (2016a: 251)

Type:— SRI LANKA. Western Province: Kalutara, Ittapana Thotupola-South End, (Ittapane-Horawala Thotupola Road), elev. 3m. 08°23.910’N / 80° 4.067’E, 15 Feb. 2015, Manawaduge & Yakandawala 215 (holotype PDA!).

Tuber cylindrical and elongate; up to 2cm Ø and 10 cm long, rarely branched. Submerged leaves lamina 17–56 × 1.4–5.2 cm; linear and slightly curved, apex acute and base cuneate, margin finely undulate, Protrude midrib with 6–8 parallel veins. Immature leaves are bright green, turn to dirty green with maturity. Petioles up to 56 cm long, brittle, bluntly triangular. Floating leaves absent. Peduncle up to 178 cm, widening towards the inflorescence. Spathe up to 35 mm, caducous. Inflorescence with 1 spike up to 15 cm long, white, densely flowered, florets turned towards all directions. Tepals 2, rounded, 1.2–2.3 × 1.3–2.5 mm, white, persistent, 1-nerved. Stamens 6, 1–2 mm, filaments slightly widening towards the base, white, anthers grayish green. Ovaries 3, white, 1.0–1.5 × 0.4–1.0 mm, often with some small excrescences, ovules 2. Infructescence up to 31 cm, dense. Folicals up to 10 × 7 mm, elongated, triangular, with rough coat and a short, terminal, curved beak. Seeds with a simple testa, relatively thick and transparent. Embryo up to 8–9 × 3–6 mm, plumule attached near the base of the embryo and in a very wide groove. Proliferous peduncles ascending up to 45 cm, slightly thickened towards the tip.

Phenology:— Flowering throughout the year. But flowering intensity increases just after the rainy season.

Distribution:— In the low land wet zone of Sri Lanka.

Ecology:— In slow flowing rivulets and rivers in much deeper water (1–2 m in some cases) and also in saline water towards the lagoons.

Uses:— Tubers, young leaves and inflorescence are eaten.

Notes:— Proliferous peduncle, the unique character of this species has been always observed in the individuals growing in close proximity to saline waters. Members growing in inland fresh waters even though they do not produce proliferous peduncle can be easily differentiated from A. crispus and A. rigidifolius , as they possess elongated tubers oppose to the globular tubers and rhizomes in the latter two species respectively.

Specimens examined:— SRI LANKA. Colombo District : Hanwella, 28 Jul. 2014, Manawaduge & Yakandawala 105 ( PDA!) ; Muthurajawela canal, 10 Mar. 1962, Amaratunga 164 ( PDA!) ; Gampaha District : Ganemulla, 24 Sep. 2015, Manawaduge & Yakandawala 126 ( PDA!) ; Yagoda , 24 Sep. 2015, Manawaduge & Yakandawala 127 ( PDA!) ; Kotugoda , 1970, Amarathunga, 2125 ( PDA!) ; Kalutara District : Meegama, 11 Aug. 2014, Manawaduge & Yakandawala 408, 409 ( PDA!) ; Lunuganga , 11 Aug. 2014 Manawaduge & Yakandawala 109 ( PDA!) ; Delgoda , 11 Aug. 2014, Manawaduge & Yakandawala 110 ( PDA!) ; Ittapane , Thotupola-South End, (Ittapane-Horawala Thotupola Road), elev. 3 m, 08° 23.910 ′ N / 80° 4.067 ′ E, 15 Feb. 2015, Manawaduge & Yakandawala 215 ; 216; 217 (PDA!); 15 Feb. 2015 Lunuganga, Manawaduge & Yakandawala 117 ( PDA!) ; Ratnapura District : Kuruwita, 17 Dec. 2015, Manawaduge & Yakandawala 128 ( PDA!) .