As a comment about Saw Greenbrier (Smilax bona-nox)
Saw Greenbriar is found in tropical, subtropical and temperate areas around the world. It is a thorny vine that climbs trees and fences and can attain heights in excess of 20 feet. It will cover shrubs and other plants forming prickly dense thickets. The green leaves are variable in shape and sometimes have yellowish blotches. The berries are an important food source for birds and other animals, and the dense thickets offer protection and shelter.
This thorny vine is considered a weed by many here in Florida. I find this plant growing in wooded scrub areas along our property line, as well as popping up and climbing around and through the chain link fence. It's hard to eradicate without digging the rhizomes which seem to go deep into the soil.