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
The Word for World Is Forest writes that Selver becomes such a god during the events of "The Word for World is Forest", but his interpretation of dreams is a negative one, because it tells the Athsheans how to kill. The Athsheans perceive the Terrans as an insane people, partly because of the disconnect amongst the Terrans between conscious, rational thinking and subconscious drives. The Terrans frequent use of hallucinogens is seen as the closest they are able to get to understanding their own subconscious. The psychological equilibrium which their dreaming gives the Athsheans is portrayed as the reason why they are able to live in