The alkaloid composition of the epigeal part of Arundo donax has been studied, and from an ether extract have been isolated the alkaloids donaxine, arundine, deoxyvasicinone, N-phenyl-β-naphthylamine, donaxarine, and donaxaridine. On the basis of an x-ray structural analysis, new structures have been established for donaxarine and donaxaridine:spiro[(N-methylpyrrolidin-2-one)-3,4′-(2′-methyl-3′,1′-benzoxazine)] and 3-hydroxy-3-(2′-aminophenyl)-N-methyl-2 pyrrolidone, respectively. Spectral characteristics of the derivatives obtained are given and their chemical interconversions are described. © 1996, Plenum Publishing Corporation. All rights reserved.