In order to spin flax or long-fibered wool, it makes it easier if the unspun is draped over a distaff.  A distaff is a stick or staff that is designed to hold those fibers.  The spinner pulls a piece from the unspun wool and begins to turn the spindle.  A thread is created and then this spun thread gathers upon the spindle.  The distaff makes the spinning process easier by keeping the fibers untangled, making for a steady flow of those fibers into the fingers of the spinner.