I'm not necessarily a big fan of Wikipedia (dependability is so inconsistent), but they seem to have a pretty good explanation of bog:

"A bog is a wetland that accumulates peat, a deposit of dead plant (and animal) material - often mosses, and in a majority of cases, Sphagnum moss. It is one of the four main types of wetlands (along with swamps, marshes, and fens)." ... "Bogs occur where the water at the ground surface is acidic and low in nutrients."

Gardeners, especially amateur gardeners, often use the term much more loosely than a biologist/botanist/etc would.

Here is a link that might be useful: Wikipedia Article on Bogs

Hi
That's the description that come s to my mind. Surprised me that KEW would use a catchall phrase lol
The plant in question is Aponogeton madagascarensis ,
grows totally subnmerged except for flowers . Would not grow at all in a "BOG" lol I suspect that it does occasionly grow as a "Marsh" plant though I doubt it.
i was looking for habitat pix . Anyway thanks for the link I've lost faith in Kew as the last word in Botany lol gary