Luckily, we decided to go nearer to confirm and was pleasantly surprised when we discovered cryptocorynes growing camouflage among the pebbles. There were both emersed and submersed forms present.
The river bed was sandy and the pH of the water was about 6.5.
Below are some close up shots of the leaves and roots.
From above you could tell that the cryptocorynes were quite deeply rooted, i.e. the white portions of the petioles were all buried within the substrate. We managed to locate a spathe with just the limb portion sticking out of the river bed and therefore had to dig out the specimen in order to photograph the entire spathe. After some discussion, we concluded that it should be C. bullosa. It was the 1st time I found C. bullosa.