Living in a marsh environment is a tradeoff for plants. On the one hand, they are protected from drought and extreme temperature variation, and they enjoy an abundant nutrient source. On the other hand, light may be inadequate, oxygen may be scarce at night, and reproduction must be modified. Despite these disadvantages, aquatic plants are so well adapted to this habitat that most are found only where there is water. This section looks at the unique strategies of aquatic plants for photosynthesis, gas exchange, support, and reproduction.
Many submergent plants have extra chloroplasts in the outer cell layers of their leaves and stems.
In contrast, terrestrial plants protect their chloroplasts with a cuticle, since strong sunlight can harm chloroplasts. These passages give the plants strong, erect stems and leaves. In floating-leaf plants, such as water lilies, air chambers in both the stems and the leaves provide buoyancy. Also, whereas terrestrial plants have stomata s on the undersides of their leaves, floating leaves have them only on the upper side. In submergent plants, air passages not only provide buoyancy but also allow for oxygen storage, to supply oxygen at night.