i have no idea what they call itbut when people turn a old t-shirt into yarn, what is the yarn called? like when people turn plastic bags into yarn its called plarn.
You also need to buy the fabric to do the needlepoint ON - and figure out how to transfer the pattern to the fabric, unless you are going to do 'counted' cross-stich (where you simply count blocks from one side or the other).
I've heard them called plaits after they are all sewn together into strips to braid into a rugI've been making and writing about recycled crafts for along time and I've always just referred to them as fabric stripsI have lots of ideas for reusing old clothes in crafts if you care to look: