An acidic heteropolysaccharide has been isolated from the tropical angiosperm Feronia limonia syn. F. elephantum (family: Rutaceae). A partially carboxymethylated alpha-(1-4) polygalacturonan backbone structure with 2- and 2,4-O-alpha-L-rhamnopyranosyl, 2- and 2, 3-O-alpha-L-arabinofuranosyl and 3-,