Aponogeton kannangarae De Silva et al. (2016: 220)

Manawaduge, Chapa G. & Yakandawala, Deepthi, 2018, Morphometrics and taxonomic update to the Sri Lankan Aponogetonaceae, Phytotaxa 365 (3), pp. 201-224 : 216

6. Aponogeton kannangarae De Silva et al. (2016: 220)

Type:— SRI LANKA. Ratnapura District, Illumbakanda dola, Morning Side, Sinharaja World Heritage Site. 6°24’27.6’’N, 80°36’37.5’’E, 1059 m, 24 Apr. 2015, Wildlife Conservation Society-Galle 1202276 (holotype PDA!).

Tuber cylindrical and elongate; up to 15 mm Ø and 11 cm long, covered with long thin roots. Submerged leaves lamina 17–38 × 3.8–8 cm; linear to lanceolate, leathery, apex and base acute or slightly cordate, margin undulate, rarely flat. Protrude midrib with 6–8 parallel veins. Immature leaves are purple to maroon, turn to dark green with maturity. Petioles up to 83 cm long, brittle, bluntly triangular. Floating leaves absent. Peduncle up to 62 cm. Spathe up to 30 mm, caducous. Inflorescence with 1 spike up to 18 cm long, dark pink and white, densely flowered, florets turned towards all directions. Tepals 2, elongate, 1–1.6 × 0.7–1.3 mm, white, persistent, 1-nerved. Stamens 6, 1–1.4 mm, filaments widening towards the base, white, anthers dark purple. Ovaries 3, white or dark pink when mature, 1.0–1.4 × 0.7–0.9 mm, ovules 2. Infructescence up to 20 cm, dense. Folicals up to 15 x 8 mm, elongated, triangular, with slightly rough coat and a short, terminal, curved beak. Seeds with a simple testa, thick and transparent. Embryo up to 7–13 × 4–6 mm, plumule attached just below the middle of the embryo and in a very wide groove.

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

Distribution:— Rakwana hills in Ratnapura District of Sri Lanka.

Ecology:— In slow flowing shallow streams.

Notes:— This species closely resembles A. jacobsenii and to a certain extent A. rigidifolius . In A. kannangarae , leaves arise as a tuft from the top of the elongated cylindrical rootstock while in A. rigidifolius the rootstock is a creeping rhizome and leaves arise along the rhizome, which is a solid character in separating them. It can be separated from A. jacobsenii as the plumule of A. kannangarae is attached just below the middle of the embryo while it is at the middle in A. jacobsenii and at the bottom in A. rigidifolius . Similarly, the leaf base of A. kannangarae is acute to slightly cordate oppose to the more or less cordate base in A. jacobsenii . But it should be noted that both these characters are not very distinct and we have observed specimens where we encountered problems in separating them.

Specimens examined:— SRI LANKA. Ratnapura District : Handapanella Plains, Sep. 1981, Gunatilleke 558x ( PDA!) ; Sinharaja , Tangamale Plains at Morningside, 12 Jan. 1993, Jayasuriya & Wijesinghe 7041 ( PDA!) ; Morningside , 27 Feb. 2012, De Silva 120227-1, 120227-2, 120227-3, 120227-4 ( PDA!). Sinharaja Aranaya, Sooriyakanda. 6°26’ 27.2” N, 80° 73’ 28.3’’ E, 23 Aug. 2014, Wildlife Conservation Society-Galle 1202275 ( PDA!) ; Illumbakandadola , Morning Side, Sinharaja World Heritage Site. 6° 24’ 27.6” N, 80° 36’ 37.5” E, 1059 m, 24 Apr. 2015, Wildlife Conservation Society-Galle 1202276 ( PDA!) .