Label from DL-{1,2- 13 C 2 ]lysine enters the two carbon atoms, C-7 and C-6, of the orchid alkaloids anosmine {6} as an intact C-2 unit. This result provides further evidence for the derivation of the alkaloid from two molecules of lysine {1}. One of these lysine units enters via cadaverine {3} and 4'-piperideine {5}, supplying the C 5 N-unit, C-13 to C-9,N-8, of anosmine, while the other generates the fragment, N-1,C-2 to C-7, by providing a C 6+ N-chain, which enters by way of pipecolic acid {4}, since 13 C from DL-{carboxyl- 13 C,(RS)-9- 2 H 1 ]}ipecolic acid is incorporated into C-7 of the alkaloid. The complete assignment of the signals in the 1 H and 13 C spectra of the alkaloid is discussed