>Teaser: What is the maximum depth in lakes for plants(Dicots/monocots only, >not byrophytes/moss liverworts etc) and why? I'll take a stab... 15 - 20 feet depending upon clarity? Why? Water adsorbs the red part of the visible spectrum, thus appearing blue. The deeper ligh penetrates, the more red it loses and I'm guessing plants need a balanced wavelength to photsynthesize. Ah...what do I know.