Natural rubber at least showed promise as rubber sources, include the rubber fig ("Ficus elastica"), Panama rubber tree ("Castilla elastica"), various spurges ("Euphorbia" spp.), lettuce ("Lactuca" species), the related "Scorzonera tau-saghyz", various "Taraxacum" species, including common dandelion ("Taraxacum officinale") and Russian dandelion ("Taraxacum kok-saghyz"), and perhaps most importantly for its hypoallergenic properties, guayule ("Parthenium argentatum"). The term gum rubber is sometimes applied to the tree-obtained version of natural rubber in order to distinguish it from the synthetic version. The first use of rubber was by the indigenous cultures of Mesoamerica. The earliest archeological evidence of the use of natural latex from the
Ficus macrophylla botanist Charles Moore described "Ficus columnaris" in 1870 from material collected from Lord Howe Island, choosing the species name from the Latin "columnaris" for the column-like roots. English botanist E. J. H. Corner reduced this to synonymy with "F. macrophylla" in 1965, before P. S. Green noted it was distinct enough for subspecies status in 1986. Australian botanist Dale J. Dixon reviewed material and felt the differences too minor to warrant subspecific status, and recognised two forms: "Ficus macrophylla" f. "macrophylla", a free-standing tree endemic to mainland Australia; and "Ficus macrophylla" f. "columnaris", a hemiepiphyte lacking a distinct main trunk