Arundo donax L. is an invasive weed found in marine and wet areas. It belongs to the family Poaceae. A. donax is usually known as giant reed. It is a rhizomatous and perennial grass that can grow to a height of 2-10 m. The root structure of this plant is very strong, with plump, almost bulbous, rhizome-forming fibrous roots that can penetrate deep inside the soil. The rhizomes of this plant grow horizontally, giving rise to hollow, many-stemmed, bamboo-like clusters, allowing it to produce large colonies. It is a destructive species that can reproduce quickly. A. donax plant is one of the world’s top hundred worst invasive alien species. It is a high-yielding non-food crop. It is native to the hot and moderate regions, and all similar climates worldwide. A. donax is a hydrophytic plant. However, it can grow in various conditions, from moist well-drained soils to those with a water table at or near the surface. The different parts of A. donax plants show a range of biological activities such as phytochemical effects. Phytochemicals identified in A. donax include triterpenoids, alkaloids, steroids, phenols, and lignins. Pharmacological effects include antibacterial, antifungal, antialgal, antihelminthic/antiparasitic, antioxidant, anti-cancerous, antiproliferative, antibiofilm, antifeedent, and toxicological activities. It also shows some ethnomedicinal effects, effects on milk production and fattening performance, effect on central nervous system, and effects on smooth muscles. So it is concluded that the plant Arundo donax L. shows various biological activities, ethnomedicinal effects, and many other effects. It contains various bioactive metabolites, carbohydrates, lignins, proteins, cellulose, hemicellulose, alkaloids, indols, fatty acids, and trace elements. It is used to treat various diseases and disorders, i.e. circulatory, dermatological, digestive, excretory, urinary, inflammatory, respiratory, skeletal, reproductive, and cancerous conditions. It has high ecological worth, i.e. in heavy metal, red mud, and wastewater treatment, as well as high economic value, i.e. in the production of medicine, paper, ethanol, construction board, and electricity, which are beneficial for animal and human welfare. © 2024 Taylor & Francis Group, LLC.