Greenbriar, are a common plant found in shady forest year-round and are identified by having both thorns and tendrils. They are also know as Catbriar or Bullbriar.
The edible parts are the young tender vines, tendrils, roots (tubers), leaves, and even berries in January. The vines and tendrils are eaten raw, baked, boiled, roasted or steamed. The roots are sliced, then pounded roasted or boiled to free starch. The berries are eaten raw (not the seeds) and can also be made into jams or jelly. Black berry jam is better, but they are not available in January.
The tubers are high in starch and minerals while the greens are high in vitamins and minerals. The youngest, lightest colored tubers are the best.
Greenbriar are usually plentiful through out most of the United States except around the Rocky Mountain range.
For additional information see the following links: