Temperature and light: The determining factors in maximum depth distribution of aquatic macrophytes in Ontario,Canada

In stratified lakes with high light penetration, the maximum depth at which macrophytes occur is frequently limited by temperature. At this depth a variety of species may be found. On the other hand, when the clarity of water limits the light penetration and the temperature at depth is sufficient for good plant growth, the plants occurring at greatest depth are ones that do not require photosynthetic oxygen for root growth. Such plants include the Charales, Isoetes, Utricularia and Ceratophyllum.