The biosynthesis of N-methylpelletierine (VII) was studied in excised shoots of Sedum sarmentosum. Consistent with classical biogenetic concepts, the piperidine nucleus of the alkaloid is generated from lysine, which is incorporated by way of nonsymmetrical intermediates, very probably ϵ-amino-α-ketocaproic acid and Δ1-piperideine-2-carboxylic acid. The propanone side-chain originates from acetate. Direct incorporation into the side-chain of an intact three-carbon unit derived from acetoacetate could not be demonstrated.