From what plant is denim made?

Denim is a sturdy cotton warp-faced twill textile in which the weft passes under two or more warp threads. This twill weaving produces the familiar diagonal ribbing of the denim that distinguishes it from cotton duck (a linen canvas). It is a characteristic of most indigo denim that only the warp threads are dyed, whereas the weft threads remain plain white. As a result of the warp-faced twill weaving, one side of the textile then shows the blue warp threads and the other side shows the white weft threads. This is why blue jeans are white on the inside. The indigo dyeing process, in which the core of the warp threads remains white, creates denim's fading characteristics, which are unique compared to every other textile.