Cassava (Manihot esculenta), also called yuca, manioc or mandioca, is the long, tapering, starchy storage root of a woody tropical shrub — a brown, bark-like skin sheathing dense, chalk-white flesh threaded by a central woody fibre. Bland, faintly sweet and intensely starchy, it is a calorie staple for hundreds of millions of people and the source of tapioca, garri and fufu; it must always be peeled and thoroughly cooked, because raw cassava carries cyanogenic glycosides that release hydrogen cyanide.