Cycnogeton rheophilum

Allied to Cycnogeton procerum but leaves usually submerged and trailing in fast-flowing water, often spiralled or undulate-margined, isolateral, thin-textured, 41–450 cm long, 2–16 mm wide, only slightly thickened basally, ± linear in cross-section c. 3 cm below the sheath summit with the width of the central portion c. 4.5–21 times its thickness and the leaf-sheaths narrow, mostly tightly inrolled, never meeting across the face of the blade (width of each usually less than one-quarter of the leaf width); leaves sometimes dorsiventral and glossy above when stranded. Scape at fruiting submerged, trailing, often semi-flattened. Fruits c. 20–232 per infructescence, ± ellipsoid in outline, 9–16 mm long, 5–9.5 mm diam.; carpels 6 (occasionally 7), normally all maturing; mature carpels ventrally attached along 63–70% of the carpel length, straight or sometimes twisted, the dorsal ridge typically prominent and narrow-convex, lateral ridges broad-convex to absent. Fruits Sep.–Feb.