Which of these plants is usually have weak-stems with numerous air spaces or wax-coated leaves?
Hydrophytes
Hydrophytes inhabit water bodies like ponds, lakes, and rivers. They have flat leaves and a thin stem which helps the plant to float. Most hydrophytes need not store water as they live in water. They have small and feathery roots. The leaves have a thin layer of wax to prevent them from rotting in the water.