Let’s start with some definitions. Anaerobic respiration means to perform respiration without air. If there is no oxygen available for the plant to survive it still needs to be able to do respiration. Respiration is the process of releasing energy from the breakdown of glucose. Aerobic respiration is respiration with oxygen. Under normal circumstances plants take in carbon dioxide through the stomata in their leaves, produce food by performing photosynthesis, and then release oxygen. At the same time photosynthesis is happening, so is respiration. During the day photosynthesis happens at a faster rate than respiration and at night respiration only takes place. Here, oxygen will enter through the stomata. If the soil gets waterlogged, the oxygen supply to plants can run out and the plants have to perform anaerobic respiration. The anaerobic respiration equation is glucose -> ethanol + carbon dioxide + energy. To sum this up, all cells need to perform respiration to produce the energy they require. In plants, if oxygen is present they will perform aerobic respiration but if it is not they still need to be able to produce energy. Producing energy without oxygen is done by anaerobic respiration.