New guinea salt fern (Asplenium acrobryum complex): identity, distribution, and chemical composition of its salt

Fronds of a fern of the Asplenium acrobryum complex were traditionally used as a source of salt in the inland areas of Papua New Guinea. All previously published reports of the use of fern salt in the botanical and ethnobotanical literature had erroneously identified the species involved as Asplenium nidus, one of the common bird's-nest ferns. A chemical analysis of the salts contained in the ash of the salt fern as well as those species related to Asplenium nidus revealed that the bulk of the inorganic component was potassium, calcium and chloride. These results are comparable to those published for the salt-yielding grass, Coix gigantean. There is no obvious chemical reason why only Asplenium acrobryum should be used for salt production in preference to Asplenium nidus and related species. In view of the low levels of consumption of such salt it is unlikely that there will be any cases of potassium toxicity attributable to the use of these plants. © 1985 The New York Botanical Garden.