Ligaria cuneifolia (R. et P.) Tiegh (Loranthaceae) is an hemiparasite species widely distributed in several provinces of Argentina. It has been commonly used in folk medicine as a substitute of the European mistetloe (Viscum album L.) based on its putative depressive effect on high blood pressure. In this paper the anatomical features as well as micromolecular and macromolecular analysis of this species are reported. Anatomical study has shown that the main characteristic is the presence of crystalliferous branched stone cells in leaves and stems. The analysis of flavonoids showed that only glycosylated quercetin and proanthocyanidins (whose monomer is cyanidin) are present, indicating a distinctive metabolic pathway. SDS-PAGE analysis evidenced a protein pattern with components ranging from 14 to 90 kD molecular weights. Antiserum against Ligaria cuneifolia was prepared in mice and its immunogenic ability was evidenced by Ouchterlony and Western-blot assays. The results presented are part of a comprehens...