The Grape Sappling is the sappling that will grow a grape tree after a certain period of time. Bonemeal can't be used to speed up the process, just be patient. This sappling can only be placed on Laterite Grass or Laterite Dirt.
These leaves only spawn on Grape Trees, and will drop a grape leaves block when harvested with a berrycollector. A shear will not work.
For easier storage you can create Grape Bushels by combining 9x Grape Leave Blocks in a craft table. The Grape Bushel will be used in the crafting recipe for Wine in a later update.
The Grape tree only spawns in the Soul Forest Biome.