The new bis-indole alkaloid arundavine, a tryptamine—tryptamine base, was isolated from roots of Arundo donax. The dimer consists of monomeric units of two known indole alkaloids, alline and bufotenine, joined through the N1 and C4′ atoms, respectively, to give the structure 8-[3-(2-dimethylaminoethyl)-5-hydroxy-1Hindol-4-yl]-1-methyl-2,3,8,8a-tetrahydro-1H-pyrrolo[2,3-b]indol-3a-ol.