Arundo donax (Gramineae) is a perennial giant grass rich in cellulose, proteins, fats, lignin, and alkaloids, and its leaf tincture is used in folk medicine as a uterine stimulant, sudorific, and diuretic. Previous studies have investigated the alkaloids of A. donax cultivated in Uzbekistan. This study continued to analyze the alkaloid composition of the epigeal part of A. donax from three growth sites: introduced plants in Samarkand Botanical Garden (full development period, total alkaloids 0.25%, main alkaloid donaxine accounting for 0.05%, 9 alkaloids isolated), wild plants in the Chirakchinskii region of Kashkadar'ya (vigorous growth period, total alkaloids 0.3%, 10 alkaloids isolated), and cultivated plants in Tashkent Botanical Garden (vigorous growth period, total alkaloids 0.36%). The results showed that the total alkaloids of A. donax from different growth sites differed in quantitative ratios and individual component compositions. The cultivated species from Tashkent and Samarkand Botanical Gardens had the same qualitative alkaloid composition and similar individual alkaloid contents. The wild A. donax from Kashkadar'ya was richer in alkaloids qualitatively, with a higher donaxine content (0.14% of air-dry plant weight) than the introduced species, making it a source for donaxine isolation. A new raw material source for donaxine hydrochloride was found in Uzbekistan.