Most are terrestrial but some plants have returned secondarily to water during their evolution. Stems and leaves are generally coated with a waxy cuticle that helps prevent loss of water. Carbon dioxide and oxygen diffuse in and out of the plants through microscopic pores in the leaf surface.
Plant cells have walls made primarily of cellulose.
Carbohydrate is stored in the form of starch, generally in chloroplasts and other cell organelles. Adaptations To obtain water and minerals from the soil, while also absorbing light and taking in carbon dioxide, these plants have both an underground root system and an above ground shoot system. Neither system can live without the other. Lacking chloroplasts and living in the dark, roots would starve without nutrients imported from the leaves of the shoot system. Conversely, leaves and stems depend on the water and minerals absorbed by roots.