Aerenchyma is a spongy tissue that forms spaces or air channels in the leaves, stems, and roots of some plants, which allows the exchange of gases between the shoot and the root. The channels of air-filled cavities provide a low-resistance internal pathway for the exchange of gases such as oxygen and ethylene between the plant above the water and the submerged tissues. Aerenchyma is also widespread in aquatic and wetland plants which must grow in hypoxic soils.
- The large air-filled cavities provide a low-resistance internal pathway for the exchange of gases between the plant organs above the water and the submerged tissues.
- This allows plants to grow without incurring the metabolic costs of anaerobic respiration.
- Some of the oxygen transported through the aerenchyma leaks through root pores into the surrounding soil.
- The resulting small rhizosphere of oxygenated soil around individual roots supports microorganisms that prevent the influx of potentially toxic soil components as sulfide, iron, and manganese.