Heliotropium supinum L. contains the pyrrolizidine alkaloids supinine, heliosupine, and echinatine as major bases. Two minor alkaloids, although not obtained in a pure state, are shown to be esters of trachelanthic acid and viridifloric acid, respectively, with 7-angelylheliotridine. The N-oxide of 7-angelylheliotridine, also isolated from the total crude base, is thought to be an artefact.Viridifloric acid is shown to be (-)-erythro-2,3-dihydroxy-4-methylpentane-3-carboxylic acid. Its melting point is markedly influenced by minute amounts of tenacious impurities. The ester of supinidine and viridifloric acid has been prepared from these component substances.