Thread wrapped horse hair.
An old form of broom was the besom, which was made simply of twigs tied to a handle, and was relatively inefficient as a cleaning implement. Flat brooms, made of broom corn were invented by Shakers in the 19th century. In the context of witchcraft, broomsticks are likely to refer to the broom as a whole. A smaller whisk broom or brush is sometimes called a duster.
Approx 14" x 4" x 1"