Aponogeton natans (Bruggen, 1985)

Manawaduge, Chapa G., Yakandawala, Deepthi & Les, Donald H., 2016, A reappraisal of leaf morphology in Aponogeton natans (Aponogetonaceae), Phytotaxa 265 (1), pp. 95-97 : 97

Aponogeton natans (L.) Engler & Krause (1906: 11)

Tuber up to 2.3 cm Ø. Leaves floating or erect up to 16 × 3 cm; base cordate, mostly unequal, seldom cuneate; apex (narrowly) cuneate with a blunt tip; parallel main nerves 5 or 7(not prominent). Peduncle up to 38 cm, not thickening towards the inflorescence. Spathe up to 15 mm, caducous. Inflorescence with one spike up to 12 cm long, densely flowered, seldom laxly flowered, scentless. Flowers turned towards all directions. Tepals 2, spatulate, 1.8–3 × 1–1.9 mm, purple, 1-nerved. Stamens 6, 2–4.2 mm; filaments not widened towards the base. Ovaries 3, up to 4 × 1.6 mm; ovules c. 8. Infructescence c. 15 cm, very dense. Folical up to 4× 1.6 mm, smooth and inflated with a very long (up to 1 mm) terminal beak. Seeds c. 1.9 × 0.7 mm with a double testa: outer one loose, winged, transparent and reticulately veined, inner one brown, closely fitting the embryo. Embryo c. 1.5 × 0.5 mm.