Minecraft wiki entry for Caves_%26_Cliffs, associated text: Grow on the bottom side of a block.
Grow in lush caves.
Can be planted using glow berries.
Produce edible glow berries, which are a light source.
Using bone meal on a cave vine produces glow berries (similar to sweet berry bushes) instead of growing the vine itself, unlike other vines.
Can be extended downward using glow berries, and has an age mechanic, similar to kelp, such that every time it ages it has a chance to grow glow berries.