I. Waterlogging of plant roots causes oxygen deficiency, resulting in the production of ACC (1-aminocyclopropane-1-carboxylic acid) in the roots. ACC is then transported to the shoots where it is converted to ethylene. II. Ethylene induces epinasty in the shoots, causing downward leaf growth and drooping, which helps drain water from the flooded roots and allow respiration to resume. III. Plants have various metabolic adaptations for coping with low oxygen conditions, including shifting carbon metabolism to ethanol fermentation and producing compounds like alanine and succinate.