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 microcarpa Ficus microcarpa Ficus microcarpa, also known as Chinese banyan, Malayan banyan, Indian laurel, curtain fig, or , is a tree in the fig family Moraceae. It is native in a range from China through tropical Asia and the Caroline Islands to Australia. It is widely planted as a shade tree and frequently misidentified as "F. retusa" or as "F. nitida" ("F. benjamina"). "Ficus microcarpa" has been described in 1782 by Carl Linnaeus the Younger. The species has a considerable number of synonyms. In 1965, E. J. H. Corner described seven varieties (and two forms of "Ficus microcarpa" var. "microcarpa") which