Other species of rubber are cooked with red achiote seeds to make a durable latex paint for adorning the body. Also known as cassava or yuca, manioc has a starchy tuber with a taste somewhat like potato. The natural source of tapioca, manioc is the most important staple crop of lowland South America. First domesticated by Amazonian peoples thousands of years ago, manioc is now cultivated in tropical areas throughout the world. Bitter manioc has high concentrations of cyanide-producing compounds, and it must be first pounded, rinsed and strained several times to remove these bitter poisons before it can be converted into edible flour and tapioca.
Sweet manioc has no such bitter compounds, and can be eaten boiled or baked like a potato.
The Machiguenga Indians of Manu use only sweet manioc. In addition to using it as food, the Machiguenga ferment mashed manioc into a beer known as ovuroki or masato, which they drink in communal celebrations. The Machiguenga and other native people of the Amazon have cultivated barbasco for thousands of years as a fish poison. When large amounts are pounded with stones and put into a stream, the milky sap of the roots interferes with the respiration of fish, leaving them stunned and floating at the surface. When the toxin wears off, stunned fish that are not captured may come back to life.