Stored in large quantities in the seeds of leguminous plants in three subfamilies. Isol. originally from Jackbean (Canavalia ensiformis) L-(+)-(S)-Canavanine is a non-proteinogenic amino acid of certain leguminous plants. It is structurally related to the proteinogenic amino acid, L-arginine. Canavanine is accumulated primarily in the seeds where it serves both as a defensive compound against herbivores and a vital source of nitrogen for the growing embryo. Organisms that consume it can mistakenly incorporate it into their own proteins in the place of arginine, thereby producing structurally aberrant proteins that may not function properly. Some specialized herbivores tolerate L-canavanine either because they metabolize it efficiently or avoid its incorporation into their own nascent proteins.; L-Canavanine, a non-protein amino acid of certain leguminous plants, is related structurally to the protein amino acid, L-arginine. Canavanine is accumulated primarily in the seeds where it serves both as a defensive compound against herbivores and a vital source of nitrogen for the growing embryo. Organisms that consume it can mistakenly incorporate it into their own proteins, in the place of arginine thereby producing structurally aberrant proteins that may not function properly or not at all. Some specialized herbivores tolerate L-canavanine either because they metabolize it efficiently or avoid its incorporation into their own nascent proteins. -- Wikipedia (unverified)