Aponogeton vallisnerioides Baker

Plants monoecious.. Tuber globular to conical, usually only 5–10 mm. (rarely to 20 mm.) in diameter; lower half greyish to greenish without roots; upper half with very numerous roots.. Leaves very numerous (often 25–50 or more on robust plants), sessile, ligulate with obtuse tips, often 10–20 cm. long and 4–8 mm. wide on larger plants, only 5–10 cm. long and 1.5–4 mm. wide on smaller specimens, without a distinct midrib, but with 7 or 9 indistinct parallel lateral nerves.. Flowers white or with a slight violet tinge, drying a warm yellowish brown, densely set in unbranched unilateral spikes on 5–30 cm. long peduncles (depending on the depth of the water); spathe 12–18 mm. long, usually persistent when flowering, caducous when fruiting.. Spike usually 2–5 cm. long and ±10 mm. wide with tepals spreading, the upper part recurved or spirally twisted; flowers inserted on only one side of the axis.. Tepals 2, white and glossy, rarely with a pinkish or mauve tinge, particularly below, oval, 3–6 mm. long and usually 2–3 mm. wide, caducous, with several nerves.. Stamens 6, 1.5–2 mm. long; filaments whitish, widened towards the base; anthers 0.4–0.8 mm. long and 0.3–0.5 mm. wide, greyish violet to blackish, but pollen yellow.. Ovaries 3, green, with 6–8 ovules.. Follicles green, 4.5–6 mm. long including a ± 1 mm. long beak.. Seeds 1.8–2.5 mm. long and 0.4–0.7 mm. wide, narrowly oblong-lanceolate with distinct longitudinal ridges (made of the loose outer testa), greenish with the brownish inner testa visible beneath.. Fig. 1.